Comprehensive Guide to Python for Data Science Course and Exam Preparation

Hello. Hello. >> Hello.

All right. That's anybody there? Hello.

>> Hello sir. >> The online class will uh when will the online class will start?

Can you see it? >> You have a question? No. So wait. >> Ah yes sir.

>> Are you able to see me? >> Yes sir I can. >> Are you able to see the screen?

Ah yes sir. >> Okay. So we are getting started now. Do you have a specific question now?

>> No sir. No sir. >> Okay then please keep yourself muted. >> Okay.

>> All right. So I hope that uh all of you can hear me and see the screen as well. If anybody's not able to hear me or see

the screen, please let me know. All right. Great. So uh my name is Sadhart Zar.

Uh so I will be one of the TAs for this course. Uh this is NOC 26/ uh CS80 that is Python for data science.

So I hope that all of you have registered for this course. So these are the logistics. First let's let me go

over the logistics briefly. So as you can see that this course aims to equip the participants to be able to

use Python programming for solving data science problems. Okay. So there are two parts to it. One is

to learn how to do Python programming and the second part is more specific is that

using Python programming how to solve data science problems. So there are two verticals.

So this is intended for final year undergraduates but I believe that it will be also accessible for

uh junior students. If you have some knowledge of basic data science that is good but that is not too

much of a constraint. So this is offered by professor

Ragunatan Reena Swami at IIT Madras. >> Is there any issue with the audio? >> No sir.

>> All right. >> Yes. So I

if you are speaking then please introduce yourself first otherwise please keep yourself muted for

the convenience of everyone. All right >> so there are four weeks in this course

myself Jasim sir. >> All right go ahead. And your voice is

not so clear. It is actually like blurry. >> Okay. So my voice is not clear. Is there

anybody else who is facing this voice issue? >> Me too sir. I also

>> sir it's clear >> actually a bit. That's it. >> No sir. For me it's clear.

>> Okay. So how many of you think that the voice is not clear? If you think that the voice is not clear, please raise

your hand. Okay. So, 5 + 6 + 7 +

8 + 9 + Okay. So there are sufficient number of people who are facing the voice issue.

I don't know if it is something with my internet. Uh

let me check. So other problem could be that I have cold. Because of cold my uh voice is

kind of shaky. So, how many of you are able to clear? >> Yes. So, now uh I want to go for another

voting. So, if you're able to hear me clearly, please raise your hand. Okay. 10 + 11 +

58 plus. So majority of the people are able to hear me clearly. So I don't think this is a connection issue. It is

because of my throat. Uh I'm having cold for a day or two. I I hope that next class onwards I will be able to speak

better. So please uh bear with me. Uh all right. So okay we we're done with the voting. We'll go ahead.

Okay. So whoever is unmuted himself please mute I cannot mute everybody one by one but

if you're unnecessarily unmuting yourself then I have to remove you from the meeting Arunit

See, I'm forced to disable the mic for Arunit because he was unnecessarily keeping himself unmuted. So, he won't be

able to speak again in this meeting unfortunately. Uh anyway,

uh so where were we? So we have four weeks in this course right. So in this four weeks we will achieve these two

goals of the course that is Python programming we learn the basics and we'll see how Python programming is used

for solving data science problems. All right. So you can uh uh so whoever has raised their hands

you can uh unra them or you can just uh how to I don't know uh remove that raise of hand. Okay.

All right. So I hope that you understand the code structure and in this course we'll have four or

five problem solving sessions like this one. So this is the first session and what we do in this session if you

have attended other NPL uh courses other NPL sessions you know uh already that we solve some

related questions specifically uh there are quizzes. So we are looking at quiz for week one in this lecture. Uh so we

are trying to give you an idea of how to solve the questions in the quizzes and the exams and to make you comfortable in

solving the problems and hope that this will help you during the exam. So the exam is optional but I strongly

encourage you to take the exam. It is at a nominal fee of 1,000 rupees and uh if you register for the exam and there is

criteria which you have to satisfy uh uh in terms of the exam score and the average assignment score then you are

eligible to receive a certificate from NPL and IT Madras. So observe that

you you have to you have to do well in the assignment. So the average assignment score should

be at least 10 out of 25 and you have to do well in the exam as well and if you satisfy only one of the criteria then

you are not eligible for the certificate. You have to satisfy both the criteria. So the assignments are

crucially important. Okay. So this is about the logistics of the course. So there are three books

which are reference books for this course which I will encourage you to read in your free time.

Uh so linear algebra is sort of the backbone of data science. So this is the

book by Gilbert Strang which is a standard textbook for linear algebra and the other books are on statistics and

probability and uh the Python programming for data science. Okay. So this is about the course. Uh you have

any questions about the course? If you have any questions about the course you can unmute yourself. Sir,

what is the last of the exam register? >> Exam registration. Okay. So, I don't

know if it is written here. Date and time of exam is March 28th. >> Sir, it's 13th February.

>> 13th February. So, someone has already uh noted down that the date for >> sir uh good evening myself Tes.

>> Yes, Tanish. Uh sir uh this is my first time of uh doing a NPL course. So can you brief something if we have to

compulsory watch the videos uh which are then on YouTube and how do we submit our assignment that and how you grant us the

marks? Okay. So you have three questions. So do you have to watch all the videos? No, it is optional. If

you're okay to take the exams without watching the videos that is absolutely fine.

uh how you submit the assignments. So we'll go to the assignments directly. So look at the left side of the screen.

Uh in week one these videos are there which you are free to watch to learn about the content. Then I'm going to

click on this quiz week one assignment one. So this will open uh the page for assignment one.

So are you able to see the questions? >> So we just need to answer the MCQs, right?

>> Exactly. >> Okay. So you choose whatever you think is right

>> and >> anyone else? Someone was trying to say something.

>> Sir, uh sir, can you tell me the exam pattern? >> Exam pattern. I believe that it is going

to be like this only MCQ and maybe there are some small uh coding questions could be there.

>> The exam actually so it will be easy for me or not. >> You are in first you are please

introduce yourself. >> Uh actually I'm sir currently doing first year.

It should be uh moderately challenging but it's doable. I believe it's doable. >> Hello. I know fundamental of Python sir.

>> Then it should be doable definitely. >> Menu. Hello. >> Yes.

>> The menu it contain total how many marks? >> This quiz

uh let me check. So one point each. So there are 10 questions. So there are 10 points for

this quiz. >> Total is for 10 marks. >> That's right.

>> Okay. Thank you. >> All right. >> Excuse me sir.

>> Can I ask you something? >> Yeah. Go one by one. Uh the lady can go first.

>> I will begin. >> My name is Kab Prasad. I am from Kerala. Actually my dou is is the exam will be

something like a choice filling or something else you have to wrote the entire program like that.

>> It's a mix of both. >> Oh okay sir. >> Next

sir the deadline for the assignment is 4th February

11:59 p.m. sir. Yeah, you we will discuss this today in the next two hours, one and a half

hours. >> Anyone else? >> Sir, any

>> Yes. Yes. Yes. Sir will we have any kind of algorithms kind of things for this course

>> uh >> like model algorithm >> let me see

so we'll we'll look at the syllabus so this is my first time doing TA for this course so let's see so in week one we

are looking at how to install the ID spider we are basically setting up the

environment uh we are seeing how to create variables then arithmetic and logical operators

data types so fine weak to mostly all the kinds of data types yes

>> uh I'm doub >> yes uh how many to say

please bit >> nothing say nothing >> okay so the previous question was

whether we will have algorithms as part of this course so I don't see algorithms specifically

uh in the syllabus yeah but there is regression okay so there is a case study on regression so

we are going to see the regression algorithm and classification algorith Hi. Hi.

>> Yes. Go. Go ahead. >> The books you have referred are available uh somewhere or how can I?

Hi Har. See if you're unnecessarily unmuting yourself, I will disable mic for you.

See, it's very easy. >> Yes. Wut. Wut. Go ahead. >> I have a small doubt, sir.

>> Okay. >> That is I have to particularly I must particularly attend this online

class. No, it is optional. Optional, sir. Yes. Can I begin?

Sir, that is not Thanking you. >> Okay, sir.

>> Oops. Yes. >> Only attending classes. Can we crack the exam?

>> I believe yes. >> Or we need to study uh the extra some like books.

I don't know for sure but I believe it should be possible to at least get past grades. Better to read but I mean I do I

understand that not too much time. Kavi Prasad you wanted to say something. >> Yes sir. Actually the books were

available in the e form. >> Absolutely. Yes. >> Okay sir. That was far more enough.

>> Okay. Um from where I think is that

you sure >> sir is it enough to watch videos and do assignment for the exam or we should

compulsory attend the online classes >> okay the online class is optional if you think that it is not helpful then you

need not come >> okay sir fine this only if you find some value in the class you can come

okay is there any other question as far as the course is concerned >> sir may I ask one question sir

>> yes please go ahead >> uh sir uh the same uh pattern for the data science and other courses deep

learning and introduction to the machine learning all these courses are available in YouTube also but it shows that it is

very older videos the recorded 8 years before 6 years before is anything need to be required to be updated or not sir

because it it is so many libraries have been updated because whatever the video lectures now it's available which is an

old recorded videos 6 years before recorded videos so many library tools have been updated so how come going to

this course will be helpful for the current scenario sir >> okay uh Sata was it Sugata

Yes sir. Yes. Yes. >> Okay. So this is a very uh interesting question. So she's saying that this

videos have been uploaded a couple of years ago. So uh whether this is this needs to be

updated. So as far as the course is concerned, this course was created by professor Ringwami a few years ago. I do

not know how many years ago. And that's when NPL uploaded the videos on NPTL. and uh the course is being repeated

every year. So as far as this course is concerned, there will not be any additions in the material of the course.

But if NPL offers a new course, a new course, then the material could be substantially

updated. So if you think that this course is already a very basic course for you, then this course may not be

helpful. If you think that this course is giving you some benefit then you attend

this course otherwise you have to wait for an advanced level course. >> Does that answer your question?

>> Yes sir. But actually know to be more proactive in this regard because this AI and machine learning

deep learning is every six months once every yearly once there will a lot of progress in it. So the course need to be

updated so that that will be really helpful for us because as we are teaching in the university level we need

to have the updated version of the this one. >> Okay. So please write an email to

professor Ringa Swami as well as NBTL and raise your point. >> Yes sir I do sir. Thank you.

>> Thank you. Okay savv sim sir. Jaz go ahead actually like for every ML and like data science and we

need first need the basics and only we can go to advance like that I guess so >> yes it depends it it depends on the

level at which you are if you're at a level where you have to learn from the basics then this is the right course for

you if you're already at an intermediate level then you have to look for another course so this is a basic course

>> okay s of chor I had muted you s we Any questions? S of you had unmuted

yourself. S of Javar >> sir do we make projects related this in future?

>> Shriti. Uh what is the question again? >> So this last last week is case study.

This is where we'll have two projects as far as I can see in the syllabus. One is on regression and the other is on

classification. Okay. Anyone else? Anything to clarify? >> Is the is the final exam online or

offline? Sir, is that Pratam Sham?

Okay. If a final exam is online, I believe that there are centers across India in selected cities. You have to

choose your city of choice preference and then you have to go to the exam center and uh appear for an online exam.

>> Sir, good afternoon. >> Good afternoon. Who is that? >> Good afternoon, sir. So, this is

Shalini. Sir, >> I just wanted to ask you. Yes, sir. I just wanted to ask you that uh regarding

the final exam which will be an online proctored exam if we get MCQs which require a little bit of working. So like

>> will we be provided with a pen? I mean or yes. Yeah. Okay. Okay. Thank you so much.

>> Yes sir. Sir actually the certification will be only available if we write the offline exam

right sir? Yes, offline means you have to go to the center online. Yes, please.

>> Okay. >> Sir, one more question. Sir, this is not related to the this course particularly.

If there is a 12 week Yeah. 12 weeks course is there then the date of examination for all the 12 week course

is on same date only because if I register for the introduction to the machine learning and deep learning both

are 12 weeks program and the date of examination is 17th uh April for both the examination. Uh for how can we give

on the same day both the papers? >> Please write an email to NPTL uh to resolve the conflict. They will help

you. >> Yes. Thank you. >> Hello sir.

>> Yes. >> I have a question about that course. >> Yes.

that NPL gives a separate uh task of us to better understanding uh task since these assignments are for

understanding only these assignments if you solve religiously then you will get a better understanding of the material.

Okay sir. Sir classes start uh first week there is no such thing as class. The the

videos you have to watch on your own and uh there are two TS including me. We will provide one session a week and in

the session we will discuss some questions. These are called problems solving sessions.

This is the format. s my question is in example. >> Okay,

go ahead >> sir. Is there any live classes? >> No, no, there are no live classes. There

live problem solving sessions only where you can ask your questions, doubts, clear your doubts and I will try to help

you. the other person who is also a TA will try to help you. >> Thank you sir. Sir my question is in

exam for Python for data science are question from linear algebra statics and calculus also asked or are only Python

reloaded question >> I think so it's a pertinent question that this is a course on Python but the

books are on linear algebra statistics probability so so the thing is the data science

subject is built on the foundations of linear algebra, statistics and probability. So there could be questions

from these topics as well. But the questions are going to be of a basic nature, of very

preliminary nature, not too high difficult questions. question

>> not know about the questions that you will get in the exam that is completely up to NPL so let me clarify I have no

affiliation with NPL and my my role in this course is limited to problem solving and doubt clearance so we will

solve problems for the last uh sorry last not last this four weeks this four weeks so first week questions are

already uh uploaded so these questions we are trying to solve will not give you exact answers but I will try to help

you. So my role is limited to help helping you in solving questions and clearing your doubts. What kind of

questions will be asked is completely up to NPL. So I cannot comment on that sir.

>> Sir is there any availability of pre questions >> sir?

>> I don't know. Uh yes good evening >> sir. We have doubt on the final online exam sir.

>> Yes. >> The in the final online exam do we have the any programming question sir?

>> So as I said I do not exactly know what is the pattern. So what I I have been TA to another Python course previously. So

what I hear is that there is a mix of MCQ and Python coding but very basic coding only I believe.

If the programming code is there we have to do in the platform like in the spider or in the Jupiter sir.

>> Yes. So in the so in the online format you will get some text box to write your code and then you write your code and

then you submit like that. >> Yes. Okay. That was my doubt sir.

>> Okay. Thank you Karthiki. >> Sir can you hear again? Come again

>> sir. Actually I first begin to take some courses something like a 12week course about gaming or something like a and ML

but I choose the this course because it feels like it was something like a 4e course and I just want to know how does

NPK works and then go to something like an 12e course or something like 16 week is it good choice

>> I don't know what works for you you have to take a call I I cannot answer that I do not know

>> okay sir good afternoon sir Good.

>> I want to know that can we use Google collab for this work? >> Yes. Yes, you can.

>> Uh there is no need of the Jupiter and the spider. >> So there is no need in a sense you need

an ID. >> Actually Google collab is easy to work online as compared to other.

>> That makes sense. That makes sense. So it depends on your choice. So the course administrator they have chosen Jupiter

and spider but you can make a different choice that is absolutely fine. >> If we do assignment on this Google is

okay. >> Yes. Yes. That's fine. >> Thank you.

>> Because you have to fill the MCQ only. How you wrote the code is up to you. If in the four fourth week there is the

case study and we want to make the assignment on Google collab then okay >> that I don't know as far as MCQs are

concerned it is fine but uh I think that it should be okay you can uh write an email to NPL for for confirmation.

>> Okay thank you sir. >> Anyone else? Anything else? Okay. So I am going to go to the

questions now. So we are going to go to the week one assignment. So how many of you have

watched the videos of week one? These videos is there anyone? Okay. So some so how

many of you have installed spider? 32 plus

33 plus 34 plus. Okay. Okay. So all all of you uh how many of you are here now? Let me

check. People are here. So we have about 35 people on wait

anyhow. So as I was saying that it is not necessary that you have to definitely

work on spider. So as far as this assignment is concerned, this assignment is

understanding the basics of Python specifically uh how to define variables and uh how to

play with simple operators. So uh we have 10 questions and these 10 questions assess your understanding of

week one that is uh operations with simple variables not not with uh derived data structures or complicated data

structures but with simple variables like integers, floats etc. Who is this person?

Catch that person. Anyway, Kumar because you have a question.

Vikas, I have muted you. But if you have a question, you can unmute yourself. But if you unnecessarily unmute yourself, I

will disable your mic. Okay. Fine. Okay. So, uh let's start with the first

question. So, it is asking which of the following variable names are invalid in Python.

So, I'll make it slightly larger. Okay. So, we have four options. So,

>> screen is not visible. Screen is not visible. Screen is not visible. Sir, can you

please share your screen? >> Screen is not visible. Uh just a second.

I'll share it again. I thought that it was visible. >> Yes, sir. Is now visible.

>> Yes, sir. Now we can >> visible, sir. >> Thank you. Thank you for pointing out.

Okay. So, you're looking at this first question. So, which of the following variable

names are invalid in? So in Python there is a convention of naming variables. You cannot name a variable in uh certain

ways. So there are some rules that you have to follow. So that is what it is asking that out of these four names

which is an invalid variable name. Okay. >> First

first option first option. So how many are how many are voting for option one? >> Please raise your hand.

>> One and four. >> One and four. So let's start one by one. So uh option one, how many are voting

for option one? 36 + 39 + 49 + Okay.

54 + Okay. So most of you think that the first name is not valid in Python. One

of you please unmute and tell me the reason >> because it start with integer number.

>> Okay. >> Identify should not start with number >> because uh it is should not start with

number. >> Right? >> Okay. So that is true only that it

should not start with the number. This is a numeric value one. Uh and that should not be the case. Right?

So how about option two? >> This is valid. >> Valid.

>> No sir. Not invalid. >> Okay. So how many of you think that option two is invalid? Please raise your

hand. because Kumar I have to disable you now. >> Disable mic.

Okay. So option two is actually valid because the name starts with u a character

which is not an integer which is not a number. So this is valid. How about option three?

>> Valid criteria for naming identifiers. >> Yes, it's a valid name for an

identifier. because it is not violating any rule. So what is the case of the fourth option?

>> Hatch not allowed. >> Valid not valid. >> Actually special characters are not

allowed sir. >> Special character is not allowed. >> That is the truth. Okay.

>> So fine. Uh so I mean you need not believe. So maybe some of you are still not happy or still not sure about uh

which one is valid and which is is is not valid. So I will show you a simple way of uh

So the deadline of submitting this assignment is not over yet. >> Mhm. No. Hi Mr. Go. So this is uh the

deadline 4th February. >> Yeah. So this is not over yet. So is this okay that the solutions are being

discussed here? Just a small point in case >> you can continue. Right.

I do not know. So how to discuss this? I do not know because this is very simple. So I'm discussing right away.

Uh yeah. Uh unfortunately the previous offering had the same assignment.

So I'm supposed to discuss the previous uh offerings assignment but unfortunately there is no difference.

uh okay so okay as Mr. Go has pointed out uh who is a veteran in NPL that I should not be directly discussing

questions that are uh still active that means whose deadlines are still not over. So I will only give

you clues from now on. Uh okay. So let's go to the second question. So which of the following operators have

lower precedence than not in Python? So I do not want you to answer the question if you know the uh answer.

>> Option C. >> Option C. >> Okay. Uh fine. So uh yeah. So which of

the following operators have lower precedence than not in Python? So let us understand the question.

>> Hello sir. Yes. Will we solve any this quiz in today's session?

>> We will not solve exactly but we will give you clues. Yes.

Okay. So, let me discuss this question. This >> Okay. So, this question is pretty

interesting. So, let me discuss this question and not give you an answer. So, which of the following operators have

lower precedence than not in Byron? So, what is not? What is not operator? Anyone

>> that get reverse the output means not true is equal to false. >> Correct. Correct.

So everyone knows what is a plus operator. It adds two numbers, two integers or two

floats. No. So not is an operator that works on a boolean variable. So a boolean variable is a

variable which can take either a true value or a false value. Not works on that. Okay. So now precedence means that

which one gets operated first. So if there are there is an expression where there are multiple operators then which

operator is evaluated first that the operator which gets evaluated first is having higher precedence than the other

operator. >> All right Mahindra

>> and is not operator sir >> not operator. Okay. So yeah, so let's see uh I will

give you only an idea. So uh so this is an online ID. This is called online python.com. So you can go

here and you can test your online python.com. You can go here and you can test your small uh python codes

snippets. Right? So I'm going to make it slightly larger for you. Zoom in.

>> Hello sir. >> Yes please go ahead. >> Will we done anything else except the

quiz in this session? >> No. If you have a doubt we can discuss it. Otherwise we'll be uh focusing on

only the questions. So here's a question. This is question number two.

So let us understand what is the notice. For example, uh if I say a = to 1

uh then this is oops what uh sorry. So if I say let's say a is equal to 2. So this is defining a variable a and

assigning it an integer two. Okay. And then let us say I want to print a. So what will I get? I run it. I get two.

So what is the type of a? What type of uh variable is a? Let me run it. It is of type int class int integer.

>> Okay. So but this not operator is specifically for uh boolean variables. So I'll write it

not operator works on >> works on true or false sir. >> Yes

that's right. So what is a boolean variable? A boolean variable as uh someone has pointed out who is that

boolean variable takes one of the two values. What are the two values? As he has

pointed out did not I did not catch his name. True and false. Karthik Karthik. So Karthik as he said so true or false

one of these two things. So, so now

so if I say not one is this valid? So let us run this.

Not only it is saying is false. So not is acting on one and it is providing false. Why is that? It should

not work on integers anyone. So not operator takes an input of two

values either zero or one. If an equation also provides an answer of zero or one,

>> it will provide a true and false output which will be a boolean. >> All right. All right. All right. So he's

saying that if you make it not zero, it will be true. That's what he's saying. And what is your name?

>> Reanir. >> Reanir. So Ranir has pointed out correctly

that if we make it not zero, it is giving true. But if I make it not one then it is giving

false. So, so, so what it turns out is that zero is actually

zero is actually equivalent to uh false and one is actually equivalent to true. Right?

Zero. >> Huh? >> Yes. Yes.

Yes. So what if I say not two? Does it make sense? Yeah. So not two is also false. So that

means two is >> Yeah. So two is behaving like true. Two is behaving like true. How about five?

Five is also behaving like true. >> Non-zero number is behave like true. >> Yes. Yes. So one anything non zero

right so can I say 5.5 oh yeah you can also say 5.5

>> this is also going to work so what it means is that anything non zero is >> true so it need not be an integer it

could be a decimal number I mean a fractional number as well okay so this is just to give an idea of how not works

So now let's look at the question again. So it is asking that which of the following operators have lower

precedence than not in Python. So I have to somehow compare not with plus to start with that whether plus has higher

precedence or not has higher precedence. So I have to construct I have to construct an expression where

both not and plus are there and then I have to check that how Python is executing the expression whether it is

executing not first or plus first right then only I'll be sure that which one has high precedence

okay so let's try to construct an expression involving plus and Not. So now,

so this is the question which of the following. So first operator we are going to look at. So first we are going

to look at plus. So see uh we are going to see how how we can construct

uh so first we are going to compare not with plus. Okay. to check precedence. So

what can I do? So let us see so first of all uh

so comparison so so this is a comparison operator. Okay. uh so so equal equal is comparison and

single equal is assignment. So if I if I say 1 + 1 is equal to 2, it should give me a boolean value that is true. But if

I ask is plus 1 + 1 equal to 3. If I make this comparison, then this will give me false. Okay. So this is a

comparison operator. Okay. So sim simple. For example, I can make it even more simple. Oh, what

happened? Yeah, I can ask is one equal to one then this gives is one equal to zero not. Okay. So now I want to sort of

mix plus and not together. Okay. So let us see

I do this. So what happened? So one one is not equal to zero. This expression gets evaluated first which gives false

and then it is negated by not. So what happens here? the sorry why? So what happened here is

that first Python evaluated this expression is 1 equal to Z and then

it followed by the not operator. So not operator was used on the output of this expression.

Okay. So it didn't do not one followed by the comparison. First it did the evaluation of this comparison operator

then it did not. So you understand? So you have to you have to tell me how I I can check

between not and plus which one has higher precedence. So can I write something here which helps me uh make

make this decision. Is the question clear? >> Yes sir. Can you can uh use an operator

like not 1 minus one? If not has higher precedence the answer will be true.

uh and if it is not if it does not have higher precedence

then the answer will be false. Okay. So you >> comparing

>> remove the as an operator also. >> So Ranir again I believe >> yes.

>> So Ranir is comparing not with minus. So he has given me an expression saying that okay let's look at this expression.

In this expression there's three operators. One is a comparison operator, one is a minus operator and one is a not

operator. So he's saying that okay how this has been computed. So what are

the possibilities? So I do not know what are the possibilities. Maybe not was not evaluated first. Maybe 1 - 1 was

evaluated first and then not was applied on the output of 1 - 1 and then the comparison took place.

That is one possibility. The another possibility is that not was evaluated first

then its output was uh so yeah so not was evaluated first then its output minus one was done and

then the comparison was was done so I do not know for sure but let us hit on the run button and see what has happened so

it is giving false so what does it The minus one has been operated first. Okay. So that means minus has higher

precedence isn't it? So if minus gets operated first then 1 - 1 is 0

and 0 is equal to 0 evaluates to false and then the negation has taken place. Isn't it?

>> No sir. First we have uh the expression 1 - 1 then we have negated after that the comparison has been taken place.

Hence it is can be false. Yes. So let us write it down. First thing that has happened is 1 - 1 which

has become zero. And then this zero this has become zero has been compared with this zero to give us a boolean

variable true. So on that true not has been operated.

So that makes the final output as false. Right? One of the other

>> this is for >> said the output of false came because the first one is printed as true and the

second expression is false. So the both uh span order has totally false sir. >> Okay. So you're saying that this

expression has evaluated has been evaluated first. That's what you're saying.

>> Yes sir. >> Okay. That is also one possibility. Karthi I believe it is Karthi.

>> Yes sir. >> So Karthi is saying that first one - one has taken place.

Then not of 1 - 1 has taken place which is true. Then there is a comparison with true.

That is what you said. >> 1 - one would have taken as true sir. So let us replace 1 - 1 by 2 and see

what happens. Ah what do you say?

Oh, true is coming up here. 1 - 1 would be false, right? >> Uh 1 - one is false means a dash

statement will be false. >> Mhm. So now there are two possibilities. Now

we are uh >> if one is true and other is false means the output will be false. Set

>> correct. So now there are two possibilities that maybe

uh the not operator has operated on this entire part or the not operator has

only operated on this part. But irrespective of that it is true that minus

has been uh computed. So the uh so this minus operator

has been evaluated before the not operator. So so the so the minus operator has

higher precedence than the not operator. Right? Because minus

has been evaluated before not write it down. minus operator

has been evaluated before or not operator.

So what is the question? Which of the following operators have lower precedence than not? So minus is not the

answer. So what what are the other options? One. Okay. So plus so let's play with plus.

So let us do plus and make it two. In the expression we have to make the output as true and we can see which is

the precedence >> in the expression

>> if we get true means we can see that is if we use minus and it comes true means and we can say it is a high

Yes. Yes. Yes. Yes. So, so now uh I I wanted to we wanted the question asked to compare not operator with the plus

operator. So that's why I have written a different expression now. So it involves plus and not. So again here I can see

that 1 + 1 has been evaluated first. Okay. >> And 1 + 1 is two. So two is compared

with two which gives true and then that is negated. So we get false. So the way you interpreted earlier maybe this is

also possible that first not is applied on two which will give false

then that is compared with two which is again give false. So what if you only apply not on this?

What if you do only this? I'm not giving you the right answer right away because as Mr. Goel pointed

out don't give the answers. So I am just showing you how to play around with the operators

uh to find out the truth. Okay. So similar thing you can do with the and

operator. So you can write an expression with the and operator. You can write an expression with the comparison operator.

And this is okay. So this one I will tell you this is a bitwise or operator. Okay. So let me give you an example.

So here is uh so uh this is the bit wise or

razia. Okay. You have a question. So anyone knows what this operator does

bitw wise or >> any of the one number is true the output will be true

that is or operator I think you're talking about this uh wait what is the let me is this

a bit wise or I have to check okay let's do this which one is or which one is it Okay,

this is invalid syntax. Uh, this is two. Uh, this is bitwise. Now make it make

sense. So let me go to the higher digit. So let's say four. Okay. Okay. So this is bitwise order. So

in in binary four is written as 1 0 0 and 2 is written as 0 1 0 right?

Anyone has any doubt on this? So I'm writing four in binary it is 1 0 0 and writing two in binary and I'm

doing bitwise all. So the third bit gets compared with the third bit and so not compared we're taking or so one or 0 is

one 0 or 0 is zero right? So second bit odd with second bit so 0 or 1 is 1. So so let me write it.

So 1 0 0 beat wise or 0 1 0 is how much? So one is compared with 0 gets 1. Second bit 0

compared with one gets one. Third bit 0 is odd with zero that is 0. So 1 0 0 1 1 0 is output

which is six in decimal. That is what we have got. So can one tell me what is

7 bit wise or two anyone? What is seven bits or two?

>> Seven. Yes. Why is that?

>> A seven is having all ones. >> Yes. Yes. Yes. Yes. So, we're taking or bit wise. This is

okay. So now uh what is the question? The question is to compare not with bitwise what? So now you have

to create an expression with bitwise or and see which one has higher residence.

So I will not give you the answer. You have to play around. Okay. Any questions?

>> No sir. >> Okay. So at this point I've seen the first two questions only.

I would give you hints for the other questions also. So in the meantime, you can look at all these questions. I think

that if you focus in the next half an hour, you'll be able to solve the next eight questions.

But for refreshments, I will give you a break now. So you'll take a short break.

5 to 6 minutes break we'll take now. And we'll be back after the break. Okay? and then we will discuss uh the

remaining questions. So, so taking a break now.

So, let us uh take a small break now. So, let's be back by 5:15

Yep. So in the next 1 minute try to think on this question three.

Am I audible? >> Yes sir. Okay,

so this question is asking what is the output of these three lines of code. So in the first line there is a

variable assignment. A gets a value of 10. B gets a value of five. Okay. So what is this operator?

Star star >> exponential Yes. >> Yes. Yes. Yes. So this is a to the power

b. So this is a to the power b. And what is this operator?

>> Modul that is modulus. >> Modulation sir. >> Yes. So this takes the remainder. So

whatever is the value here divides it by three and outputs the remainder. for example

one sir. >> Okay. So I I I I would prefer that you keep the answers to yourself. I'm just

explaining the question because as Mr. Gu pointed out the due date is still a few days away.

I'm just explaining the questions. So this is uh asking that uh if you expon if you take the exponent

exponentiation of a to b and take uh the remainder when divided by three what will be the remainder? Okay. Okay. So

any any doubts on this question? >> No sir. >> No sir.

>> Okay. Please keep the answer to yourself. Uh okay.

So let's move on to the next question. So what will be the output of the following code snippet? Here is a

variable greetings which is assigned a string variable. Namaste. Then again >> I have one doubt.

>> Yes, please go ahead. >> In second question answer is bit by and sir.

>> In this question what is the answer you asking? >> And

>> uh I do not know the answer. In fact, I I would not be uh it'll be unethical to give you the answer right away because

uh the deadline is away. I I cannot tell you the answer. But if you think the answer is end, I it's good. I we'll

discuss the answer later only. I already give you uh you know some clues. >> Okay, sir.

>> Yes. Yes. This is for the sake of integrity and uh ethical behavior. I'm not giving away the answers.

So here's a variable which is given a string v value. Here is another variable which uh takes

the previous variable which is a string variable converts it into a float and then in this third line

you are asking what is the type of the second variable. So I I don't want you to give the

answer. So but this is the question. If there is any doubt on the question we can discuss that.

It is converting one data type to another data type, sir. >> Yes. Yes. Yes. That is true. And then

>> option is C. >> Okay. I do not know the answer. Maybe it is C. I don't know.

Uh >> it will throw an error. Maybe that is also possible

number. >> Okay. Okay. Maybe that is true. I cannot tell you the answer.

Uh Mr. wanted to say something. Sir I in

this process the conversion of data type or something what we call it >> it is type conversion only type

conversion. Yes. >> Okay. Uh so what are the what are the rules of type casting in Python like

which variables can be type casted and so what is the general rule of type casting in Python like say uh can we

type cast an int to float or float to int uh and so what what are the general rules

and to what extent we would be losing the precision uh if we type cast in a wrong direction.

>> Okay. So uh let's uh play around. So let us say I I take uh

I take an integer. Okay. I don't have to say this is a Python. So A4. So I ask what is its type?

and it says it's integer. Now let's uh type cast float

and then let's print p now. So I get 4.0. So uh now it it is it has

been converted into float. So it's possible to convert into float. the other way will also be plausible.

Uh so what gets uh so your question is which types are compatible which with

which other types when it comes to uh conversion? >> Yes. Yes.

>> So it depends. So there are so simply by

the simplest ways to convert float to int and into float and maybe I don't know maybe we can play with characters

also. Uh let us see if that works. Okay so

I think oh the other way around will work. Maybe if I just sit this and then I

get Yeah. So I I haven't

Oops. Oh, there's typo. Yeah. So int has been converted to string. I haven't necessarily checked

with all pairs of uh types but the simple things generally work that into float character uh string to uh sorry

integer to string but it is more more with common sense I think that you know of course there's this Python manual

where you can look up things but I haven't really checked things so thoroughly

>> 10 possible extreme into float. So let's say this is a string and I change it to float.

Looks okay. But yeah, this is possible. But if the

string is made up with characters, then there is an issue. >> Yes. Yes. And do we have anything

equivalent of size of like say size of in C++ to know the the size >> size? Yes. Size only. I think size will

work. >> Oh, I see. So let's say I want to ask size

uh no so this way v dot size let us see wait uh size is not quite You know

what would what precise >> sir sir I think we have uh alien function

>> okay okay length let's see what is it like this btl length

uh but len should be for the itles I guess this will not >> that is not Right. Yeah, that is for its

size of >> uh like we use size of in C++ to know just to know that how how many I mean

how many bytes are occupied for a particular data type. >> Yeah, there is no harm in asking Google.

Get size off. That's what it is saying. It's a great size of >> Oh, I see. Yeah.

So, you have to import this package s then only it will work. You have to do sis.get size of yes right here.

>> Unlike see size off and this thing has some limitations also. H oh I think this pass by reference and

pass by value are slightly different in Python that's why it's looking at shallow size and the other details are

there >> yes yes uhhuh

so let us move on to the next question so here you have two variables one is an integer and the other is uh float.

So what is normal division and what is float division? So if I divide 6 by 3.3

normally what will I get? So if I divide 6 by 3.3 then I get

Yeah. Please go ahead. Yes. So normal division means you simply

divide. So 6 by 3.3 is 1.81818 and so on. And if I do uh sorry

>> load division is the approximate sir 6 / 3 to 4 to 1.5 approx one

okay so so if I take the floor the fractional part is removed in the

floor division. Yeah, this this is not working anyway.

Uh yeah. So, so what is the question? So, six by 3.3 is 1.81 that value and 6 by 3.3

with floor is simply one. So, I'll write it down. So uh 6 / by

3.3. Okay. Why is it showing plus size? Uh is that number

and uh and six. So floor division is in Python is like this with double slash by 3.3. This will

give you the integer part of the division value. Right?

So the fractional part is removed as someone has pointed out. Thank you for pointing out.

So what is the question again? There is some I joined late in the class. What

happened before the break? Okay. There are so many questions already. Yeah. So

what would be the data type of the value obtained from the operation? So again you can play around.

Uh maybe I will not show you the answer because just simply by playing around you can tell the answer. So this is a

question. Is there any doubt on the question? >> No just a simple question.

>> Yes. What would be a minimal difference between integer and float? What is the question again?

What would be a minute difference between integer and float? >> Okay, we'll take the questions one by

one. So first question you are asking is what is the difference between integer and

float? >> Integer and float. >> Okay.

So integer means whole numbers and float means you can have fractional numbers. Okay. For example, if I tell you that a

is equal to 4.5, that means by default Python Python will know that the data type of A is float

because there are fractional part in this number. So when I'll print type of A, let me remove all these things.

>> I think it clarifies me. Thank you for that. I I understood combining the two concepts I I was able to answer the

question. >> Okay. Okay. Fine. Okay. So there is another question.

He said uh what did he say? If I divide integer with integer

by an integer can we get fruit? That is the question. I think that is the question. And

someone else was asking in Hindi. Yeah. So we can So for example if I divide

Yeah. Go ahead. Then I get a fractional number which is

2.5. Right. >> All decimal numbers comes out of flo.

That is true. That is correct. Okay. So shall we move on to the next

question? I think 27th class would be a repetition of today's class for those who haven't

attended today's session. Okay, maybe that is true. What will be the output of the following

code? We are moving to the sixth question. So here is a. So this is an assignment of the string 1 zero to a.

Then there is float conversion. So now it becomes float. Then you add five to it. Then you again convert it to

string. Then you concatenate that string with 1 2 3. And then you ask what is the type of this variable result.

That is what is happening. So you understand these four lines error. Okay, maybe that is true.

>> It is error sir. >> All right. All right. Fine. So keep the answers to

>> what will error sir. >> Okay. Maybe the reason you can keep to yourself. Maybe it will not be an error.

I do not know. Uh but I explain to you what is happening in each of these lines.

Uh right. >> Uh so what if instead of 10 uh it is 10 r then if I type cast this uh a as a

float >> then it will fail. >> Oh I see. All right.

Uh it it won't be extracting the float value out of history. No.

>> Let us try. So it could not convert a string to float,

>> right? But 10 is 10 is still a string but the only thing is that it comprises of only noodles.

>> Yes. Yes. Yes. In that sense. Yeah. Yes. Yes. Right. Okay. So we'll move to the next

question. What will be the output of the following code snippet? This is question number

seven. A gets 15, B gets three, C gets four. And then there is an expression and the

expression is evaluated. So you have to understand what these okay so this is plus this is multiplication

this is floor division which I already said. So for example if I write

five okay let's not do so many things just simply write

five. If I write 5 by two then what do I get? these things

then I get 2.5 but if I write five division 2 then I get two that is only the integer part after the division

so you have to evaluate these things and report the result

this is modulus takes remainder is that fine >> it is a flow division

There is no boolean operator here. There is no end. So you have to tell what is the

precedence that which happens first, which happens next, which operator has more precedence that you have to

understand and you can play around with it. Multiplication comes first.

>> Okay. Yes. Then you evaluate it. Don't tell me the answer. Keep it to yourself. Answer.

Uh so you can choose answer and you know I don't know what is the answer and then submit. You can submit as many times as

you like before the deadline. Fine. So we move to the next one. What is the output of the following code

snippet? So A gets four, B gets five. Okay. So this one I will tell you. So Mhm.

>> So this is like saying that multiply b2 and then multiply a with b2 and give to

a. >> So the >> the answer sir

>> okay anyway I don't know so I will uh prefer that you keep the answers to yourself.

Let me explain the uh this operator. So this operator is

simply a short hand. For example,

if I write a= 5 into 2 or let's take another. So let's say a= b a equal to 4 and uh I'll say

that 2 into a is b. Okay. Uhhuh. So then I print B.

Then I get 8. And then I write that. Okay. Let's do one thing. Let's multiply whatever is in