How to Reset Index of Pandas DataFrame?

Pandas Reset Index of DataFrame

When you concatenate, sort, join or do some rearrangements with your DataFrame, the index gets shuffled or out of order.

To reset the index of a dataframe, you can use pandas.DataFrame.reset_index() method.

Syntax of reset_index()

The syntax of DataFrame.reset_index() function is given below.

DataFrame.reset_index(level=None, drop=False, inplace=False, col_level=0, col_fill='')

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To reset the index, pass the parameters drop=True and inplace=True.

Example 1: Pandas Reset Index of DataFrame using reset_index()

In this example, we will concatenate two dataframes and then use reset_index() to re-order the index of the dataframe.

Python Program

import pandas as pd
	
df_1 = pd.DataFrame(
	[['Somu', 68, 84, 78, 96],
	['Kiku', 74, 56, 88, 85],
	['Ajit', 77, 73, 82, 87]],
	columns=['name', 'physics', 'chemistry','algebra','calculus'])

df_2 = pd.DataFrame(
	[['Amol', 72, 67, 91, 83],
	['Lini', 78, 69, 87, 92]],
	columns=['name', 'physics', 'chemistry','algebra','calculus'])	

#concatenate dataframes
df = pd.concat([df_1, df_2])
#now the index is not in order

# reset index
df.reset_index(drop=True, inplace=True)

#print dataframe
print(df)

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Output

Example 2: Pandas Reset Index of DataFrame using concat()

You can reset the index using concat() function as well. Pass in the argument ignore_index=True to the concat() function.

Python Program

import pandas as pd
	
df_1 = pd.DataFrame(
	[['Somu', 68, 84, 78, 96],
	['Kiku', 74, 56, 88, 85],
	['Ajit', 77, 73, 82, 87]],
	columns=['name', 'physics', 'chemistry','algebra','calculus'])

df_2 = pd.DataFrame(
	[['Amol', 72, 67, 91, 83],
	['Lini', 78, 69, 87, 92]],
	columns=['name', 'physics', 'chemistry','algebra','calculus'])	

#reset index while concatenating
df = pd.concat([df_1, df_2], ignore_index=True)

#print dataframe
print(df)

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Output

   name  physics  chemistry  algebra  calculus
0  Somu       68         84       78        96
1  Kiku       74         56       88        85
2  Ajit       77         73       82        87
3  Amol       72         67       91        83
4  Lini       78         69       87        92

If you have only one dataframe whose index has to be reset, then just pass that dataframe in the list to the concat() function.

Python Program

import pandas as pd
	
df_1 = pd.DataFrame(
	[['Somu', 68, 84, 78, 96],
	['Kiku', 74, 56, 88, 85],
	['Ajit', 77, 73, 82, 87]],
	columns=['name', 'physics', 'chemistry','algebra','calculus'])

df_2 = pd.DataFrame(
	[['Amol', 72, 67, 91, 83],
	['Lini', 78, 69, 87, 92]],
	columns=['name', 'physics', 'chemistry','algebra','calculus'])	

#concatenate
df = pd.concat([df_1, df_2])
#now the index is not in order

#reset the index
df = pd.concat([df], ignore_index=True)

#print dataframe
print(df)

Run this program

Video Tutorial – Reset Index of Pandas DataFrame

Summary

In this Pandas Tutorial, we learned how to resent index of Pandas DataFrame.