How to print rolling window equation process from pandas dataframe in python?

Question

I created a pandas dataframe sample and it tried to sum for every 3 rows:

import pandas as pd
import numpy as np

d={\'A\':[100,110,120,175,164,169,155,153,156,20         


        

Answer 1

It's a little bit tricky to get rolling to work with conditional string output

equations = []
df.A.rolling(3).apply(lambda x: equations.append(f'{x.sum()} = {x.iloc[0]}+{x.iloc[1]}+{x.iloc[2]}') or 0)
df.loc[2:, 'equations'] = equations
print(df)

Out:

     A                  equations
0  100                        NaN
1  110                        NaN
2  120  330.0 = 100.0+110.0+120.0
3  175  405.0 = 110.0+120.0+175.0
4  164  459.0 = 120.0+175.0+164.0
5  169  508.0 = 175.0+164.0+169.0
6  155  488.0 = 164.0+169.0+155.0
7  153  477.0 = 169.0+155.0+153.0
8  156  464.0 = 155.0+153.0+156.0
9  200  509.0 = 153.0+156.0+200.0

Answer 2

d={'A':[100,110,120,175,164,169,155,153,156,200]}
df=pd.DataFrame(d)
for ind in df.index:
        if ind == 0 or ind == 1:
            print("NaN")
        else:
            sumOf3Numbers = df["A"][ind-2]+df["A"][ind-1]+df["A"][ind]
            print("{}={}+{}+{}".format(sumOf3Numbers,df["A"][ind-2],df["A"][ind-1],df["A"][ind]))