Subset df by last valid item

Question

I can return the index of the last valid item but I'm hoping to subset a df using the same method. For instance, the code below returns the last time 2 appears in the df. But I want to return the df using this index.

import pandas as pd

df = pd.DataFrame({              
    'Number' : [2,3,2,4,2,1], 
    'Code' : ['x','a','b','c','f','y'],                          
    })

df_last = df[df['Number'] == 2].last_valid_index()

print(df_last)

4

Intended Output:

   Number Code
0       2    x
1       3    a
2       2    b
3       4    c
4       2    f

Answer 1

You can use loc, but solution working only if at least one value 2 in column:

df = df.loc[:df[df['Number'] == 2].last_valid_index()]
print (df)
   Number Code
0       2    x
1       3    a
2       2    b
3       4    c
4       2    f

General solution should be:

df = df[(df['Number'] == 2)[::-1].cumsum().ne(0)[::-1]]
print (df)
   Number Code
0       2    x
1       3    a
2       2    b
3       4    c
4       2    f