Python Pandas - Fill NaN with Linear Interpolation

To fill NaN with Linear Interpolation, use the interpolate() method on the Pandas series. At first, import the required libraries −

import pandas as pd import numpy as np

Create a Pandas series with some NaN values. We have set the NaN using the numpy np.nan −

d = pd.Series([10, 20, np.nan, 40, 50, np.nan, 70, np.nan, 90, 100]) 

Find linear interpolation −

d.interpolate()

Example

Following is the code −

import pandas as pd import numpy as np # pandas series d = pd.Series([10, 20, np.nan, 40, 50, np.nan, 70, np.nan, 90, 100]) print"Series...\n",d # interpolate print"\nLinear Interpolation...\n",d.interpolate()

Output

This will produce the following output −

Series... 0   10.0 1   20.0 2    NaN 3   40.0 4   50.0 5    NaN 6   70.0 7    NaN 8   90.0 9  100.0 dtype: float64 Linear Interpolation... 0 10.0 1 20.0 2 30.0 3 40.0 4 50.0 5 60.0 6 70.0 7 80.0 8 90.0 9 100.0 dtype: float64