Pandas Series: diff() function

First discrete difference of element in Pandas

The diff() function is used to first discrete difference of element.

Calculates the difference of a Series element compared with another element in the Series (default is element in previous row).

Syntax:

Series.diff(self, periods=1)

Parameters:

Returns: Series
First differences of the Series

Example - Difference with previous row:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series([2, 2, 3, 4, 5])
s.diff()

Output:

0    NaN
1    0.0
2    1.0
3    1.0
4    1.0
dtype: float64

Example - Difference with 3rd previous row:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series([2, 2, 3, 4, 5])
s.diff(periods=3)

Output:

0    NaN
1    NaN
2    NaN
3    2.0
4    3.0
dtype: float64

Example - Difference with following row:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series([2, 2, 3, 4, 5])
s.diff(periods=-2)

Output:

0   -1.0
1   -2.0
2   -2.0
3    NaN
4    NaN
dtype: float64

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