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Pandas DataFrame interpolate() Method

❮ DataFrame Reference


Example

Replace NULL values with the number between the previous and next row:

In this example we use a .csv file called data.csv

import pandas as pd

df = pd.read_csv('data.csv')

newdf = df.interpolate(method='linear')
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Definition and Usage

The interpolate() method replaces the NULL values based on a specified method.


Syntax

dataframe.interpolate(method, axis, inplace, limit, limit_direction, limit_area, downcast, kwargs)

Parameters

The parameters are keyword arguments.

Parameter Value Description
 method 'linear'
'akima'
'barycentric'
'cubic'
'cubispline'
'from_derivates'
'index'
'krogh'
'nearest'
'pad'
'pchip'
'piecewise_polynomial'
'polynomial'
'quadric'
'slinear'
'spline'
'time'
'zero'
'bfill'
'pad'
'ffill'
None
Optional, default 'linear' . Specifies the method to use when replacing NULL values
axis 0
1
'index'
'columns'
Optional, default 0. The axis to fill the NULL values along
inplace True
False
Optional, default False. If True: the replacing is done on the current DataFrame. If False: returns a copy where the replacing is done.
limit Number
None
Optional, default None. Specifies the maximum number of NULL values to fill (if method is specified)
limit_direction 'forward'
'backward'
'both'
Optional, default 'forward', (if the method is backfill or bfill, the default limit_direction is 'backward'. Specifies the direction of the filling.
limit_area None
'inside'
'outside'
Optional, default None. Specifies restricitons of the filling:
None - No restrictions
'inside' - Fill only NULL values inside valid values
'outside' - Fill only NULL values outside valid values
downcast Dictionary
None
Optional, a dictionary of values to fill for specific data types

Return Value

A DataFrame with the result, or None if the inplace parameter is set to True.


❮ DataFrame Reference