# Category Archive Step By Step Python Training Tutorial

### How to plot Boxplot in Python

A box plot is used to visualize 5 values in a dataset for the selected column(s):

• Minimum Value
• First Quartile or 25%
• Median (Second Quartile) or 50%
• Third Quartile or 75%
• Maximum value

Box Plot is also known as Box and Whisker Plot.

Steps –

1. Load the dataset using Pandas dataframe
2. Select any column to visualize
3. Plot boxplot using Pandas
OR
4. Plot boxplot using Seaborn

Python Code :

import pandas as pd

index age gender bmi children smoker region charges id
0 19 female 27.900 0 yes southwest 16884.92400 1
1 18 male 33.770 1 no southeast 1725.55230 2
2 28 male 33.000 3 no southeast 4449.46200 3
3 33 male 22.705 0 no northwest 21984.47061 4
4 32 male 28.880 0 no northwest 3866.85520 5
5 31 female 25.740 0 no southeast 3756.62160 6
6 46 female 33.440 1 no southeast 8240.58960 7
7 37 female 27.740 3 no northwest 7281.50560 8
8 37 male 29.830 2 no northeast 6406.41070 9
9 60 female 25.840 0 no northwest 28923.13692 10

data.describe()

age bmi children charges id
count 1338.000000 1338.000000 1338.000000 1338.000000 1338.000000
mean 39.207025 30.663397 1.094918 13270.422265 669.500000
std 14.049960 6.098187 1.205493 12110.011237 386.391641
min 18.000000 15.960000 0.000000 1121.873900 1.000000
25% 27.000000 26.296250 0.000000 4740.287150 335.250000
50% 39.000000 30.400000 1.000000 9382.033000 669.500000
75% 51.000000 34.693750 2.000000 16639.912515 1003.750000
max 64.000000 53.130000 5.000000 63770.428010 1338.000000

# In pandas boxplot one attribute, column is required to plot boxplot
# Column can take name of one column of the dataset or the list of columns
data.boxplot(column=[‘age’],figsize=[10,7]) # We can group data as well.

data.boxplot(column=[‘age’], by=[‘gender’], figsize=[10,7])

# Boxplot Using Seaborn Library

### Maths Module in Python Language

How to Import Maths Module in Python

Maths module is already included with python installation.

To import any module in your program you must use:

import <modulename>

To import Math module write:

>>>import math

Example

>>> print(pi)

NameError: name ‘pi’ is not defined

>>> import math

>>> print(math.pi)

3.141592653589793

>>> print(pi)

NameError: name ‘pi’ is not defined

We must use math. before calling any method or variable of math module.

>>> math.factorial(5) # To calculate factorial

120

>>> math.e

2.718281828459045

### Typecasting in Python – Changing Data Types in Python

Typecasting in Python

It is the process of changing one datatype to another data type.

Functions used to do typecasting.

str(x) – To change x to string

int(x) – To change x to integer ( x must be float or bool but not complex or string)

float(x) – To change x to float ( x must be int or boolean)

complex(x) – To change x to complex number. ( x must be numeric or bool)

bool(x) – To change values to True or False ( 1 is true and 0 is False )

Here x is the variable which has to be typecasted.

>>>X = “15” # Here x is string

>>>type(X)

<class ‘str’>

>>> print(int(X))

15 # X is now integer

### Taking User Input in Python Language

How to Take User Input in Python

We can take user input in python using the console window or we can also create GUI using python.

To create GUI windows in Python we use a library or module called Tkinter.

To take user input in python using console window we use and built in function called:

input()

Example:

name = input(“Enter Name”)

# Here name is the variable where we want to store of the value which user will enter in the console screen.

“Enter Name” is an instruction to user.

input() function creates string values only.

Example :

name = input(“Enter Name”)

if(name==”Mohan”):

print(“Welcome Mohan”)

if(pwd==”123″):

else:

print(“You are not mohan”)

Exercise : Create a program in python to calculate the area of a triangle.

a=float(input(“enter a in cm”))

b=float(input(“enter b in cm”))

c=float(input(“enter c in cm”))

s=(a+b+c)/2

print(“area is ” ,(s*(s-a)*(s-b)*(s-c))**0.5, “cm^3”)

input()

### Comparison Operators in Python Language

Comparison Operators

In programming comparison operators are used to compare two or more values. These are comparison operators used in Python.

1. Equals To – “==”

To check whether one value is equal to other value.  The answer is returned in Boolean format.

Example:

>>> name = “Mohit”  # Assignment

>>> name == “Mohit”  # Comparison

True  # Output

>>> x = 5  # Assigment

>>> 5 == x  # Comparsion – LHS is equal to RHS here

True

*Use of If Condition

Syntax of if

if(condition):

statement

Example

>>> name = “Ramesh”

>>> if(name == “Ramesh”):

#indentation block

print(“Welcome Ramesh Babu”)

Welcome Ramesh Babu  #output

1. Greater than: “ > “

>>> x = 67

>>> if(x > 65):

print(x, ” is greater than 65″)

67 is greater than 65

Example with With if and else :

x = 68

if(x > 65):

print(x , ” is g t 65 “)

else:

print(x , ” is ngt 65 “)

# 68 is g t 65

1. Greater than or equal to

Example :

>>> t = 678   # assignment

>>> t >= 789 # comparison

False              # output

>>> t >= 678

True

>>> t >= 677

True

1. Less Than

>>> cb = 56

>>> cb < 45

False

1. Less than or equal to

>>> cb = 56

>>> cb <=  56

True

>>> cb <=  78

True

### Assignment Operators in Python Language

Here are the Assignment Operators in Python Language

Assignment Operators are used to assign values to variables. In simple words, putting value in a variable. These values can be of any data type.

1. Equal to Operator – ‘=’

Equal to operator is used to assign any value to a variable.

Example –

>>> x = 5

>>> name = ‘Mohit’

Here value of 5 (integer) is assigned to variable x

Value of  Mohit (String type) is assigned to variable name.

Note – the value to be assigned (defined) should be written on right hand side of = sign.

Here x = 5  is correct but 5 = x is incorrect.

See an example:

>>> a = 65

>>> b = a

>>> print(b)

65

>>> u = 65

>>> u = v #Will raise Error

See Example

>>> x = 56

>>> x += 56

>>> print(x)

112

Here x + = 56 means x = x + 56

1. Assignment with Subtraction

>>> g = 58

>>> g -= 8    #   g = g-8 | g = 58 – 8

>>> print(g)

50

We are assigning a value of g – 8 to g itself.

1. Assignment with multiplication

>>> a = 4

>>> a *= 5   # a = a * 5

>>> print(a)

20

1. Assignment with Division

>>> df = 45

>>> df /= 5   # df = df / 5

>>> print(df)

9.0

### Arithmetic Operators in Python Language

Arithmetic Operators

1. Addition – ‘+’ – To Sum two or more numbers

>>> x = 56

>>> y = 45

>>> x + y

101

1. Subtraction – ‘-’ – To Subtract two or more numbers

>>> a = 345

>>> b = 123

>>> a – b

222

1. Multiplication – ‘*’ – To find the product of two or more numbers

>>> u = 45

>>> v = 3

>>> u * v

135

>>> a * b * u

1909575

1. Division – ‘/’ – To divide two or more numbers. Answer is always a float.

>>> people = 6

>>> quantity = 42

>>> quantity / people

7.0

1. Exponentiation – ‘**’ – To find y raised to power of x or vice versa.

>>> x = 5

>>> y = 2

>>> y ** x

32

>>> x ** y

25

1. Modulus – ‘%’ – To find the remainder in any division.

>>> x = 22

>>> y = 7

>>> x / y

3.142857142857143

>>> x % y  # Finding the remainder

1

>>> 343 % 4

3

1. To Find Quotient in Division – ‘//’

>>> 343 / 4 # Division

85.75

>>> 343 % 4 # Remainder

3

>>> 343 // 4 # Quotient

85

### Operators in Python Language

Operators in Python language

Operators are used to perform specific actions in programming languages.  Here are names of some common operator in Python:

1. Arithmetic Operators ( Also known as math operators )
2. Assignment Operators ( To assign values to variables )
3. Comparison Operators ( To compare value of two or more variables )
4. Logical Operators ( To combine multiple operations logically )

### Variables in Python – Tutorial

Variables are used to store values in Python. These variables can be used later on in the program for computing purpose.

Variables have a name, value and a memory location in computer.

For Example:

X = 56

Here X is the Variable Name and 56 is its value.

= is known as assignment operator.

The meaning of this statement is – A value 56 of integer datatype has been assigned to a variable named X.

Another Example :

>>> name = “Rohit”

Here variable name is name

Here value of variable is “Rohit”

>>> type(name)

<class – str>

How to Print a Variable

>>> print(name)

Output : Rohit

We can use variables to perform mathematical operations.

>>> x = 56

>>> y = 67

>>> print(x + y)

Output : 123

Variable values can also be changed.

>>> name = “Mohan”

>>> print(name)

Mohan

>>> name = “Sohan” # We have changed the previously assigned value.

>>> print(name)

Sohan

You can call variables – value-holder.

These values can be of any datatype.

>>> # Valid Variable Names

>>> first_name = “Mohan”

>>> FirstName = “Mohan”

>>> Firstname = “Mohan”

>>> firstName = “Mohan”

>>> # Invalid Variable Names

>>> first name = “Mohan” # using spaces is not allowed in variable names

SyntaxError: invalid syntax

>>> first-name = “Mohan” # using – sign means subtraction so it is not allowed

# No symbol is allowed except _ (underscore)

>>> We cannot start a variable name with number

>>> 1name = “Mohan” # invalid

>>> name1 = “Mohan” # valid

### Python Tutorial Part 3 – Basic Syntax of Python

In the previous part of this tutorial we explained the process of installing Python on your computer. In this tutorial we will explain about the Basic Syntax of Python language.

Once Python is installed in your computer you can use one of the following tools to code and execute python. You can search for Python in your computer programs and you will find these two options.

IDLE is an integrated development environment for Python.

Other One is the Command Prompt Windows for Python Coding.

IDLE is a preferred option for Python Coding because it has a Coding Editor with built in auto suggest tool. It has nice color coding to differentiate between various elements of a code.

### Basic Syntax of Python – How to Print a Statement in Python

Python Uses a built-in function named print to print any statement.

If we want to print “Welcome to Python Tutorial” we can use the following command.

print (“Welcome to Python Tutorial by Slidescope”) You can see the Screen Shot of IDLE Window.

The line with three Greater Than Signs >>> is the input line

The next line in Blue is the Output.

You can see the Statement to be printed is written in Round Brackets and Double Quotes.

You can also use single quotes.

Value written inside Quotes Represent a String Data type.

To print integer or float type values we don’t have to use single or double quotes.

Syntax to Print an Integer Value:

>>>print (55)

Output:  55

After writing the Input we have to press enter to execute the command and present output.

Please try using these commands in your practice and let us know if you have any doubts in the comment section below.

If you are not familiar about Data Types in Programming Languages then Refer to Our Next Tutorial which explains the data types topic.

Official Website of Python Is www.Python.org