iloc in Python with Syntax and Examples

As we all know that python is widely used for data science. Python has excellent support for data science. Also, python provides a wide range of data science libraries for different kinds of operations. One of them is Pandas. The pandas library is the most favorite library for data scientists. The Pandas make data analysis way simpler than other libraries.

The pandas library provides many inbuilt functions to make operations on the data set. An iloc is one of its functions. The iloc in python is used to retrieve rows from the data set. This function is used when the indexing in the data set is not a number (0,1,2,3,4,…,n) or when the user does not know the exact name given to the index.  

Syntax of iloc in python : 

pandas.dataframe.iloc[]

Parameters: 

1. Index position 
2. Return type

Example of iloc function in python

Example

import pandas

mydict = ({'Brand' : ['Lamborghini', 'Mustang', 'Porsche', 'BMW'],
          'Year' : [2012, 2014, 2011, 2015],
          'City' : ['Pune', 'Delhi', 'Mumbai', 'Delhi'],
          'Mileage' : [5, 8, 12, 15]})

data = pandas.DataFrame(mydict)

Printing data of index 1 and 3

print(data.iloc[1])
print(data.iloc[3])

Output

Brand      Mustang
Year          2014
City         Delhi
Mileage          8
Name: 1, dtype: object
Brand        BMW
Year        2015
City       Delhi
Mileage       15
Name: 3, dtype: object

Printing data from range 1 to 4 using the slice operator

print(data.iloc[1:4])

Output

     Brand  Year    City  Mileage
1  Mustang  2014   Delhi        8
2  Porsche  2011  Mumbai       12
3      BMW  2015   Delhi       15

Printing records by passing boolean values to the iloc function.

print(data.iloc[[True,True,False,True]])

Output

Brand  Year   City  Mileage
0  Lamborghini  2012   Pune        5
1      Mustang  2014  Delhi        8
3          BMW  2015  Delhi       15

Printing name and year of a car

print(data.iloc[0,[0]],"\n", data.iloc[0,[1]])

Output

Brand    Lamborghini
Name: 0, dtype: object 
 Year    2012
Name: 0, dtype: object

What is the difference between loc and iloc in python pandas?

The loc and iloc in python are predefined in the pandas library. Both the functions are used to retrieve data from the data set. We will see the difference between both functions with an example.

Example

Importing pandas package

import pandas as pd

Creating a list of dictionaries

mydict = [{'Name': 'mars', 'number': 4, 'distance from sun':228000000, 'moon count': 2, 'life' : False},
        {'Name': 'earth', 'number':3 , 'distance from sun':150000000, 'moon count': 1, 'life' : True},
        {'Name': 'Jupiter', 'number': 5, 'distance from sun':757060000000, 'moon count': 53, 'life' : False},
        {'Name': 'saturn', 'number': 6, 'distance from sun':14000000000, 'moon count': 82, 'life' : False},
        {'Name': 'venus', 'number': 2, 'distance from sun': 1070000000, 'moon count': 0, 'life' : False},
        {'Name': 'mercury', 'number': 1, 'distance from sun': 460000000, 'moon count': 0, 'life' : False}]

Converting it into a data frame

data = pd.DataFrame(mydict)

loc() :

The inbuilt loc() function is a label-based function. We can retrieve the data using labels given to the column and row. The loc() function accepts the boolean data unlike iloc() function. We can make many operations of the data frame using the loc function in python, like selecting specific rows, selecting rows within a range, adding constraints, etc.

1. Selecting column with an attribute name

Example :

print(data.__getattr__('Name'))

Output

0       mars
1      earth
2    jupiter
3     saturn
4      venus
5    mercury

2. Selecting rows index-wise.

Example

print(data.loc[[0,2,4]])

Output

Name  number  distance from sun  moon count   life
0     mars       4          228000000           2  False
2  Jupiter       5       757060000000          53  False
4    venus       2         1070000000           0  False

3. Selecting rows in range using the slice operator

Example

print(data.loc[1:4])

Output

Name  number  distance from sun  moon count   life
1    earth       3          150000000           1   True
2  Jupiter       5       757060000000          53  False
3   saturn       6        14000000000          82  False
4    venus       2         1070000000           0  False

iloc() :

The iloc in python is an index-based function. It is used when the programmer does not know the index name of the data set. We can not use the name of the index in this function. We have to pass the index number as a parameter to the function. The iloc function helps to retrieve the data from specific rows and columns. The iloc() function does not accept the boolean data like loc(). We will learn this function considering the above data set.

1. Selecting different row using indexing

Example

print(data.iloc[[1,2,4,5]])

Output

Name  number  distance from sun  moon count   life
1    earth       3          150000000           1   True
2  jupiter       5       757060000000          53  False
4    venus       2         1070000000           0  False
5  mercury       1          460000000           0  False

2. Selecting row within range using the slice operator

Example:

print(data.iloc[1:4])

Output

Name  number  distance from sun  moon count   life
1    earth       3          150000000           1   True
2  jupiter       5       757060000000          53  False
3   saturn       6        14000000000          82  False