[Tutor] Unintentionally manipulating a list

[ranjan das]

I am facing the following problem


I have a list of the form

INPUT= [ [ ['A1-N','A2-Y','A3-N' ],['B1-Y','B2-N','B3-N' ] ], [.........] ]


and I want an output of the form (selecting only those elements which have a
Y associated with them)

OUTPUT=[ ['A2-Y', 'B1-Y'],[....] ]


I wrote the following code. Although it gives me the desired output, it
CHANGES the list INPUT

now after i run the code I get INPUT as the same as OUTPUT (which i dont
want to happen). I have used the copy function but it still is not working.
Any help or pointers is appreciated

*CODE*

from copy import copy

temp=copy( INPUT )
OUTPUT=temp



for i in range(len(temp)):

    for j in range(len(temp[i])):

        for k in range(len(temp[i][j])):

            if temp[i][j][k][-1]=='Y':

                OUTPUT[i][j]=temp[i][j][k]
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