LEARNING DATA SCIENCE , PART 3

 DATA TYPES IN PYTHON  

1. NUMBERS -

Integers i.e whole numbers , not decimal

2. FLOAT

Floats are the decimal numbers . Example - 4.3 , 5.7 

3. Complex Number 

x + iy  , here x = real number and y = imaginery

4. Boolean

Boolean is either true or false 

5. SET 

Set is a collection of data

Set only contains unique elements , repititions are not allowed.

6. DICTIONARY

 It states in the from of key and it's value terms.

{name : 'John , Age:'25' , 'city':25 , 'New year'}

7. STRING

It is the most commonly used data type. Write in between of commas "   ".

8. LIST 

List is collection of items and it can have duplicate items.

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

9. TUPLES 

Tuples are immutable ( means we can not modify the code once written).

10. NONE 

 When the type of data does not exist that is known as NONE .

Now, we will move forward to PYTHON OPERATORS 

1. ARITHMETIC OPERATORS

#ADDITION (+)

 a + b (operand), here a = operant and b = operator.

# SUBTRACTION ( - )

  a = 20

  b = 8 

 result = a - b 

print (result)

   12

# MULTIPLICATION (*)

  a = 3

  b = 3 

 result = a* b 

 print ( result) 

#DIVISION (/ ) 

   a= 24 

   b = 3 

result = a/b 

print( result)

(Python always returns answers in float i.e decimals)

# MODULUS (%)

 a = 17

 b = 4

result = a % b 

print ( result) 

 1 ( output )

#EXPONENTIATION ( ** )

  a= 5

  b = 2 

 result = a**b ( **= power)

  print (result)

 25 

~ COMPARSION OPERATORS

# Equal to ( ==)

This operator determines if 2 values are equal or not .

 a = 10

b = 5

result = a ==b 

print (result)

False.

# Not Equal to ( !=)

 a = 3

 b = 3

result = a!=b

print(result)

False

# GREATER THAN ( > ):

    a = 12

     b = 8

      result = a > b 

     print (result)

     True 

# Less than (<):

  a = 5

   b = 8

    result = a < b 

   print ( result) 

   True 

# GREATER THAN OR EQUAL TO (>=)

    a = 12

    b = 12

   result = a >= b 

    print ( result)

# LESS THAN OR EQUAL TO ( <= )N

   a = 10 

   b = 15

  result = a < = b

 print( result) 

True 

~ LOGICAL OPERATORS 

  # Logical AND (and) 

 x = True 

y = False 

result = x and y 

print ( result)

# Logical OR 

 x = True 

 y = False 

result =  x or y

print (result)

True 

# LOGICAL NOT ( NOT)

x = True 

result = not X

print(result)

False

~ ASSIGNMENT OPERATORS

Assigning some value to a value 

# Assignment (=)

 a = 20 

# Additional assignment ( +=)

  a += 5

  print (a)

   25

# Multiplication assignment (*=)

    a+= 4

    print(a)

    80

#Division Assignment (/=)

   a /= 3

print(a)

33.33333333

~MEMBERSHIP OPERATORS

 This tries to search or look up and it returns BOOLEAN ( True or False)

# ' in' operator

text= "Data Science Course is available in PWskills"

result = "Data Science" in text 

print(result)

True

# not in operator 

 text= "Data Science course is available in PWskills "

result = "Data Science" not in text

print (result)

False

# IDENTITY OPERATORS

# 'IS' operator 

It is used to check if two items are same ( T or F )

x = 'PWskills'

y = x 

result = x is y 

print (result)

True

# 'is not' operator 

x = 'PWskills'

y = x

result = x is not y 

print (result)

False

PYTHON OPERATORS PRECEDENCE AND ASSOCIATIVITY

1. PARANTHESIS ()

It is used to make calculations easier 

Example 1 - Using paranthesis to change order of operations 

result = (2+3)*4 , paranthesis ensure addition is done first.

Example 2 - Grouping expressions for clarity 

total = (10+5) + (8/2)

print (total)

19.0

2. EXPONENTIATION **

This indicates power of the number 

Example 1 - Calculating 2 to the power of 3 

result = 2 ** 3

print(results)

8

3. BITWISE SHIFT OPERATORS  <<(Left shift operator),  >> ( Right shift operator)

1. Example - Left Side 

   result = 8 << 2

   print (result)

    32

#shifts 8 two bits to the left 

2. Example - Right shift 

Value = 32

Shifted = Value >> 32  

print(shifted)

#shifts 32 two bits to right .

PYTHON CONVERSION  

1. Converting integer ( int())

#Convert a float to an integer 

  float_num = 10.5 

  int_num = 10.5 (float_num)

print(int_num)

10

 # Convert a string to an integer 

    str_num = "42"

    int_str = int(str_num)

    print (int_str)

     42

----- If you type str_num = 'FIVE' and then try to convert it to integer, it will show error as python can convert word to number.

2. Converting to float (float ())

 #Convert an integer to a float 

int_num = 34

float_num = Float (int_num)

print (float_num)

 type(float_num)

#Convert a string to a float 

 str_num = "2.12"

float_str = float (str_num)

print(float_str)

 2.12

3. Converting to string (str())

   # Convert an integer to a string

   int_num = 32

   str_num = str (int_num)

    print(str_num)

     32

    #Convert a float to a string 

     float_num = 2.89

      str_num = str(float_num)

     print (str_num)

      2.89

4. Converting to Boolean (bool())

# Convert an integer to a boolean

  int_num = 0

  bool_num = bool (int_num)

  False 

#Convert a non- empty string to a boolean

   non_empty_str = "PWskills"

   bool_str = bool(non_empty_str)

   print (bool_str)

#Convert an empty string to a boolean 

  empty_str = '   '

   bool_empty_str = bool(empty_str)

   print (bool_empty_str)

-- CONDITIONAL STATEMENTS

1.   IF 

course = "Data Science"

if course == 'Data Science'

 print( "You are on the right track!")

  You are on the right track!

Example  - 

1. Pwskills_ grades = 8

If Pwskills_grades >= 7

  print ( "Impressive Pwskills!")

Impressive  PWskills

2. marks = 90 

  if marks >= 90

    print ("You got an 'A' grade)

3. number = 42 

if number %2 ==  0 

print ( "The number is even")

 4.  age = 15

 if age >= 18

print( "You are not an adult)

 5. Score = 69 
  passing_score = 70

if score >= passing _score 

     print ("Congratulations , you passed)

else :

if score >= passing_score 

print("You did not pass.")

 You almost passed,


2. 'if - elif -else' statement

 It is used in situations where you have to choose among multiple choices .

 Course = "CS" 

if  course == 'Data Science' 

   print ("You are in PWskills Course")

elif Course == "Physics"

   print (" You are in physics wallah's course)

else

  print ("You are not enrolled in any course")

 3. Nested 'if else' Statement 

  Course = 'Data Science '

    grades = 7

if course = = "Data Science"

 if grades >= 7

  print("Impression skills in Data Science at Pwskills!")

  

LOOPS

LOOPS are used when we want to repeat some code or to do things multiple times.

1. 'for' loop 

 # Printing a list of courses 

Courses = [ "Data Science" , "Data Analytics" , "Python" , "Javascript" ]

 for courses in course:

  print(Course)

#Generating a number sequence 

Variations of range

1. range(n) 

for i in range (5) ....this indicates that it will iteriate 5 times 

i = 0 , 1, 2 , 3 , 4

range (n) ---- [ 0,1 ,2 , n-1]

2. range (2,7)

2 - this indicating starting and 7 indicates last one

    = [2,3,4,5,6] 5 elements

#Generating a number sequence

for i in range (1,6):

   print("Number" , i )

           Number : 1

           Number : 2

           Number : 3 

           Number : 4 

           Number : 5

3. range (1, 10, 2) , (It will start from 1 , 2 indicates how many jumps will be there in sequence)

                (1,3,5,7,9)

 Courses = ["Data Science " , "Data Analytics" , "Python" ]

        print (f"Course {count}: {course}"]

        count +=1

      print(count)

   course 1 : Data Science

   course 2 : Data Analytics

   course 3 : Python

2. Nested 'for' loop

When we introduce a new loop under a loop it is called nesting.

#Multiplication table 

 for i in range (1,6)

    for j in range (1,1,1)

         product = i * j

       print (f " {i} * {j} = { product}")

       print ()

# Printing a pattern 

  for i in range (5)

    for j in range (i + 1)

       print(* , end = " " )

       print()

for i in range (5):

  print (i , end ", ")

   0,1, 2, 3, 4

#Printing a pattern  

for i in range (5)

  for j in range ( i + 1)

     print ("*" , end = " " )

     print ()

#Creating a matrix -- 2 Dimensions

  rows = 3

 cols = 3

 matrix = []

for i in range(rows)

  row= []

for j in range (cols)

   row.append ( i * cols + j )

      matrix.append (row)

for row in matrix 

\print (row)

  [ 0,1,2 ]

  [3,4 ,5 ]

  [6,7,8]

# Matrix multiplication

matrix A = [ [1,2,3] ,[4,5,6] , [7,8,9] ]

matrix B = [ [9,8,7] , [ 6,5,4] , [ 3,2,1]

result = [ [ 0,0,0] , [0,0,0] , [0,0,0]

 for i in range (len (matrix - A )

  for j in range (len (matrix - B ) [0])

   for k in range (len (matrix - B ) 

     result [i] [j] += matrix - A [i][k] * matrix -B [k][j]

     for row in result 

 'WHILE' LOOP 

#Printing course names until it meets the conditions

Course = [ " Data Science" , "Data Analytics" , " Python" ]

  index = 0

while index < len (courses)

  print( courses [index] 

    index +=1 

#Counting Down 

    count = 5

  while count > 0 

     print (count)

    count = 1

# Right triangle 

  row = 1 

while row <= 4

  col = 1

while [col < = row :]

   print ( '*'  , end = "  ")

   col +=1 

 print()

row+= 1

#Square 

 side = 1

while side = 1

    width <= 1 

     while width <= 3 

         print ("*" , end = "  ")

         width += 1

          print ()

         side += 1 

So in this 




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