Boolean Indexing in Python

The Boolean values like True & false and 1&0 can be used as indexes in panda dataframe. They can help us filter out the required records. In the below exampels we will see different methods that can be used to carry out the Boolean indexing operations.

Creating Boolean Index

Let’s consider a data frame desciribing the data from a game. The various points scored on different days are mentioned in a dictionary. Then we can create an index on the dataframe using True and False as the indexing values. Then we can print the final dataframe.

Example

 Live Demo

import pandas as pd # dictionary game = {'Day':["Monday","Tuesday","Wednesday","Thursday","Friday"], 'points':[31,24,16,11,22]} df = pd.DataFrame(game,index=[True,False,True,False,True]) print(df)

Running the above code gives us the following result

Output

               Day       points True        Monday           31 False      Tuesday           24 True     Wednesday           16 False     Thursday           11 True        Friday           22

Using .loc[]

This function can be used to filter out records that has a specific Boolean value. In the below example we can see fetch only the records where the Boolean value is True.

Example

 Live Demo

import pandas as pd # dictionary game = {'Day':["Monday","Tuesday","Wednesday","Thursday","Friday"], 'points':[31,24,16,11,22]} df = pd.DataFrame(game,index=[True,False,True,False,True]) #print(df) print(df.loc[True])

Running the above code gives us the following result

Output

              Day points True       Monday 31 True Wednesday 16 True Friday 22

Using .ix[]

In this method we also use integers as Boolean values. So we change the True and False values in the dataframe to 1 and 0. Then use them to filter out the records.

Example

 Live Demo

import pandas as pd # dictionary game = {'Day':["Monday","Tuesday","Wednesday","Thursday","Friday"], 'points':[31,24,16,11,22]} df = pd.DataFrame(game,index=[1,1,0,0,1]) #print(df) print(df.ix[0])

Running the above code gives us the following result:

Output

 Day points 0 Wednesday 16 0 T hursday 11