Python Dataframe New Column With Value Based On Value In Other Row

I have another simple question as a follow up from here. Python pandas dataframe sum numbers until they change I want to analyze a serie of numbers which go up and down. So far I h

Solution 1:

Here you are:

import numpy as np
df['LastTB'] = (df.A * df.TB.replace({'':np.nan, 'T':True, 'B':True})).fillna(method="ffill")
df['C'] = df.A / df.LastTB.shift()

and the output is:

    A  UD  ST TB  LastTB         C
0800NaNNaN12-1-1  B     2.0NaN24112.02.00000035122.02.5000004613T6.03.00000054-1-16.00.66666763-1-2  B     3.00.5000007511T5.01.6666678500T5.01.00000093-1-15.00.600000102-1-25.00.400000

If you are determined to write in one line, you can combine both lines:

df['C'] = df.A / (df.A * df.TB.replace({'':np.nan, 'T':True, 'B':True})).fillna(method="ffill").shift()