With Pandas Calculate Diff , but with different columns

Question

Give Data As

import pandas as pd
import numpy as np
df = pd.DataFrame({"Start": [1, 4, 8, 12], "Stop": [2, 6, 9, 13]})
# Calculate df['lag'] = Previous[Stop] - This[Start]

Lag = NA for first Row. Else Lag = Current Row Start - Previous Row Stop

Output:

df = pd.DataFrame({"Start": [1, 4, 8, 12], "Stop": [2, 6, 9, 13],"lag":[np.nan,2,2,3]})

It_is_Chris · Accepted Answer · 2023-02-01 19:43:16Z

3

You are looking for shift

df['lag'] = df['Start'] - df['Stop'].shift()

   Start  Stop  lag
0      1     2  NaN
1      4     6  2.0
2      8     9  2.0
3     12    13  3.0

answered Feb 1, 2023 at 19:43

It_is_Chris

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