How can I append a new list to an existing list?-CodePudding

So I'm trying to add a new list to my original list of lists, aka grid, and here is my code,

board = [
    [" "," ","1"," "],
    [" "," ","1"," "],
    ["1","1"," "," "],
    ["1"," "," ","1"]]
def total1count(board: list):
    t = []
    for x in board:
        t.append(x.count("1"))
    return sum(t)
s = (list("1"*total1count(board)))
print(board.extend(s))

However, when I run the code, the output returns None... why is that??

CodePudding user response：

Extend just modifies the list, you cant print it.

board.extend(s)
print(board)

CodePudding user response：

Array.extend(Array2) did not return anything (means none) that's why the output is none. if you want to print board you need to run board.extend(s) first than print board

board = [
[" "," ","1"," "],
[" "," ","1"," "],
["1","1"," "," "],
["1"," "," ","1"]]
def total1count(board: list):
    t = []
    for x in board:
        t.append(x.count("1"))
    return sum(t)
s = (list("1"*total1count(board)))
board.extend(s)
print(board)