How to Replace a single, unknown, index in a 2d list in python

Question

How would I be able to replace a single index in a 2d list if we don't know what value is currently in that location?

Initially, i thought

twoDList[0][0].replace('A')

would work; however, it does not. So what is the proper way to replace an index in a 2d list in python?

` #Craft a 2d board board = [['.' for a in range(rowNum)] for b in range(columnNum)] #Iterate through each row for i in range(rowNum): #Iterate through each column for j in range(columnNum):: board[i][j].replace('A') ` rowNum and columnNum are user inputed constants — Donnie B
– Donnie B, Commented Nov 10, 2015 at 23:50
I don't understand if you want to insert A and you don't care about the old value or you want to only replace a value the value in 2d list if it is A? — napkinsterror
– napkinsterror, Commented Nov 10, 2015 at 23:59

R Nar · Accepted Answer · 2015-11-11 00:28:13Z

1

.replace does not do in place replacements since strings are immutable, rather it returns a copy of the string. make sure to set the new value to the item:

tw0dList[0][0] = 'A'

edited Nov 11, 2015 at 0:28

answered Nov 10, 2015 at 23:55

R Nar

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2 Comments

Donnie B Over a year ago

i still get the error TypeError: replace() takes at least 2 arguments (1 given)

R Nar Over a year ago

i wasn't even thinking, i relooked at your question and it looks like you dont want to be using replace. correct me if im wrong but do you just want the value at twodlist[0][0] to be 'A'? i editted it to do that

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