Module I - Day 1

Wroking with jupyter environment

There are two types of cells in jupyter notebook 1. Markdown cell - in which you can type a text or information like this cell 2. code cell - in which you can type python code and then execute it

You should know this - by default a new cell is code cell - esc + m will convert that cell in to markdon cell - esc + y will convert the cell into code cell - shift + enter will execute current cell

Basics of python programming

Numeric Data

42 + 42 # it has integers

42 * 43 # multiplication

45 / 2

22.5

45 // 2 # integer division

2**5 # power

5 % 2 # modulus operator , remainder when divided what ever is on right side

1.2 + 4.2 # real number .. we call it float in python

5.4

5.0 * 2.0

10.0

5.0 * 3 * 45

675.0

5 * 3 * 45

see the difference in results.. one is float/real number and another is integer

operators have priorities just like in excel or what we know from mathematics

1 + 4 * 5 # multiplication/division/modulus have higher priority as compared +-

4 * 5 ** 2  # highest priority is for power

(1+4)*5 # you can adjust the priority by puting bracket

4 * 5 % 2 # * will be executed first and then % ..

If operators of same priority are there in a statement then which ever comes first (left) will be executed first

Text data

"this is text data" # this is text data

'this is text data'

'this is also text data' # data in single quotes is also text

'this is also text data'

"this is ' # this is syntax error

SyntaxError: unterminated string literal (detected at line 1) (800093987.py, line 1)

"this has to start with double quote and end with same"

'this has to start with double quote and end with same'

'similarly you can start with single quote and end with'

'similarly you can start with single quote and end with'

"you can have special chars like \n \t \\"

'you can have special chars like \n \t \\'

"c:\Program Files\Python3.10" # this is not correct because \ has a menaing in python text data

'c:\\Program Files\\Python3.10'

"c:\\Program Files\\Python3.10"

'c:\\Program Files\\Python3.10'

"hello"*5 # this means repeate the string 5 times

'hellohellohellohellohello'

"hello " + "world" # concatenate

'hello world'

"hello" + 'world'

'helloworld'

"He said, 'I am fine with quote!'"

"He said, 'I am fine with quote!'"

"a string with double quotes at both ends can have single quote ' inside the text"

"a string with double quotes at both ends can have single quote ' inside the text"

'a string with single quotes on both side can have double quote inside"the text'

'a string with single quotes on both side can have double quote inside"the text'

'can not have single quote ' here ' # because the second quote here is eneding the string

SyntaxError: unterminated string literal (detected at line 1) (3036092906.py, line 1)

"hello"*-4 # it resulted into empty string

''

"hello"*-1

''

"*"*5

'*****'

n = 5

"*"*n # this I expect as five stars

'*****'

n = -1
"*"*n

''

"hello" + 5

TypeError: can only concatenate str (not "int") to str

Problem

Compound interest calculated as using this formula P(1+r/n)^nt.

P = principle amount
n = number of times a year the interest is compounded
t = number of years
r = rate of interest

P = 26780
r = 7%
n = 4
t = 5

2(3+5)

<>:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
<>:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
/tmp/ipykernel_1729313/740595946.py:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
  2(3+5)
/tmp/ipykernel_1729313/740595946.py:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
  2(3+5)
/tmp/ipykernel_1729313/740595946.py:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
  2(3+5)

TypeError: 'int' object is not callable

2 3 # python does not understand what to do with these two number

SyntaxError: invalid syntax (162316803.py, line 1)

2 + 3

(3+5)

2 (3+5) # it doesn't know that 2 and result of bracket should be multiplied

<>:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
<>:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
/tmp/ipykernel_1729313/1144834379.py:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
  2 (3+5) # it doesn't know that 2 and result of bracket should be multiplied
/tmp/ipykernel_1729313/1144834379.py:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
  2 (3+5) # it doesn't know that 2 and result of bracket should be multiplied
/tmp/ipykernel_1729313/1144834379.py:1: SyntaxWarning: 'int' object is not callable; perhaps you missed a comma?
  2 (3+5) # it doesn't know that 2 and result of bracket should be multiplied

TypeError: 'int' object is not callable

2*(3+5)

# in one code cell you can write multiple lines
P = 26780
r = 0.07
n = 4
t = 5

26780*(1+ 0.07/4)**(n*t)  # P(1+r/n)^nt

37887.76008234032

X = 10
Y = 20

X # this will show what is in X

Y # this will show what is in Y

X + Y

X * 2

P = 26780
r = 0.07
n = 4
t = 5

P*(1 + r/n)**(n*t)

37887.76008234032

result = P*(1 + r/n)**(n*t)

result

37887.76008234032

Variables and Literals

"X" # this is not variable X, this is string "X"

'X'

X is variable
“X” is literal string

m = 2 # m is variable and 2 is literal

n = m + 2 # here again n and m is variable and 2 is literal

5 # literal 5

five = 5 # here five is variable

Rules for name of a variable

The variable name can not be a number
The varibale name can not start with a number
It can not have hyphen or any operator in the name
it can have alphabets, numbers and underscores

twice - valid
x2 - valid
2x - invalid
x_2 - valid
_x  - valid
__x__ - valid
x^2 - invalid
x-2 - invalid

vikrant = "my name"

vikrant # variable

'my name'

"vikrant" # is a literal

'vikrant'

"hello jskhdkjsa dsf kdhfkjds  fkjdhf dsk"

'hello jskhdkjsa dsf kdhfkjds  fkjdhf dsk'

vikrant

'my name'

a, b = 2, 3 # you can assign two variables at a time

first, last = "vikrant","patil"

first

'vikrant'

last

'patil'

x, y, z = 1, 2, 3 # only condition is it has to seperated by comma

x,y = 1, 2, 3

ValueError: too many values to unpack (expected 2)

x, y, z = 1, 2

ValueError: not enough values to unpack (expected 3, got 2)

quiz

x = 10
y = x
x = x + 10

what will be the value of y after this

x = 10
y = x
x = x + 10

x = 10
y = x
y = 25

value of x?

x = 10
y = x
y = 25

Y # python is case sensitive so Y and y are taken different variables

more on text data

name = "Arcesium" # there is some text  data in a variable called name

What if I want to access elements of this text

name[0] # in python 0 is the start

'A'

name[1]

'r'

name[4]

's'

name[7]

'm'

name[-1] # what this can be

'm'

name[-1] # if -ve number is given indexing will start from other end of text data!

'm'

     P  Y  T  H  O  N
 ->  0  1  2  3  4  5
    -6 -5  -4 -3 -2 -1   <---

s = "PYTHON"

s[0]

'P'

s[-6]

'P'

s[-1] # last element

'N'

Collection

The data types that we saw as of now are called basic basic data types. Then there are higher level data types which is nothing but collection of basic data types.

List List is collection where you can put together many objects serially.

[1, 2, 3, 4, 5]

[1, 2, 3, 4, 5]

nums = [1, 2, 3, 4, 5]

nums

[1, 2, 3, 4, 5]

nums[0] # just like text/string you can access nth item from the list

list_of_words = ["one", "two", "three"]

list_of_words

['one', 'two', 'three']

list_of_words[0]

'one'

list_of_words[-1]

'three'

list_of_mix = [1, 2, "hello", "world", "one"]

list_of_mix[0]

list_of_mix[4]

'one'

words # there is no such variable defined

NameError: name 'words' is not defined

another_list = [list_of_words, nums]

another_list # it is has two elements ... two lists.. list_of_words, nums

[['one', 'two', 'three'], [1, 2, 3, 4, 5]]

another_list[0] # what will be this?

['one', 'two', 'three']

another_list[1]

[1, 2, 3, 4, 5]

another_list[0][0]

'one'

another_list[0][-1]

'three'

name = "vikrant"

name[0]

'v'

bignumber = 6578423

bignumber[0] # this will not give me first digit!

TypeError: 'int' object is not subscriptable

bignumber_str = "6578423"

bignumber_str[0]

'6'

bignumber*2

13156846

bignumber_str+2

TypeError: can only concatenate str (not "int") to str

bignumber_str*2 # this will concatenate it two times

'65784236578423'

list_of_words[0] # square bracket

'one'

list_of_words(0) # round bracket has different meaning

TypeError: 'list' object is not callable

Just like strings, you can have * and + operators working on list

nums

[1, 2, 3, 4, 5]

nums +  nums

[1, 2, 3, 4, 5, 1, 2, 3, 4, 5]

nums * 5

[1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5]

nums

[1, 2, 3, 4, 5]

nums[-1]*3

5*3

nums

[1, 2, 3, 4, 5]

nums[0]

dictionary

We have a different collection kind of data structure where objects can be saved with name and values. Dictioanry is collection of key and value. Key is string most of the times (but not necessary), value can be anything

scores = {"rupali":20 , "alice":19, "maya":18, "kavya":20}

scores['rupali']

scores['maya']

scores['kavya']

listscores = [20, 19, 18, 20]

listscores[0] # score of zeroth student

scores

{'rupali': 20, 'alice': 19, 'maya': 18, 'kavya': 20}

scores['kavya']

stock = {'name':"IBM", "open":123, "high": 126, "low":120, "close":123.5}

stock

{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5}

stock['name']

'IBM'

stock['close']

123.5

Ket things to remember about brackets

To make a list we use square bracker []
To make a string we use single or double quotes
To make dictionary we use curley brackets {}
to access element from a list/string/dict/ you use [] after the variable
to access element from string/list you use [] brackets after variable but use number as index inside the bracket
to access element from dict you use [] brackets after variable but use key(usually string) as index inside the bracket

ibm = {'name':"IBM", "open":123, "high": 126, "low":120, "close":123.5}

apple = {'name':"APPLE", "open":143, "high": 146, "low":140, "close":143.5}

ibm

{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5}

apple

{'name': 'APPLE', 'open': 143, 'high': 146, 'low': 140, 'close': 143.5}

stocks = [ibm, apple]

stocks  # is a list of dictionaries

[{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5},
 {'name': 'APPLE', 'open': 143, 'high': 146, 'low': 140, 'close': 143.5}]

stocks_dict = {"IBM": ibm, "APPLE": apple} # dictionary of dictionaries!

stocks_dict['IBM']['close']

123.5

stocks_dict['APPLE']['close']

143.5

stocks

[{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5},
 {'name': 'APPLE', 'open': 143, 'high': 146, 'low': 140, 'close': 143.5}]

stocks[0]['close'] # this give close value from zeroth dictionary

123.5

stocks[0] # this is nothing but a dictionary

{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5}

stocks[0]['name'] # so next level you access just like dictionary

'IBM'

stock['name'] # I am giving 'name' as literal

'IBM'

stock

{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5}

stock['exchange']

KeyError: 'exchange'

k = "name"

stock[k]

'IBM'

name

'vikrant'

stock[name]

KeyError: 'vikrant'

because the variable name has value “vikrant”… so it resulted into stock["vikrant"]

d = {"x":[1, 2, 3, 4, 5] , "y":"something simple ..text"}

d['x'] # is a list

[1, 2, 3, 4, 5]

d['y']

'something simple ..text'

Functions

stock

{'name': 'IBM', 'open': 123, 'high': 126, 'low': 120, 'close': 123.5}

nums

[1, 2, 3, 4, 5]

len(nums) # how many elements are there in nums?

len(name) # how many letters are in name?

len("vikrant")

len("hello")

len(stock) # how many key,value pairs are there?

print(name)

vikrant

print("Hello World!")

Hello World!