Lists containing number

user_13077487 0
Viewed 101

I'm trying to write a loop that checks whether a certain number in lists in a list is not appearing. For example: if I have the list 

[[1,'O', 3], [4, 5, 6], [7, 8, 'X']]

I want to write a loop that checks whether number 2 appears in one of the lists, and if not, asks you to pick a new number. So far I'm stuck on this:

move = 2
for i in range(3):
    for j in range(3):
        if move not in board[i][j]:
            move = int(input("Number already taken. Pick another"))

But it doesn't work. It seems to be a fairly straightforward check, but I don't know why it wouldn't run. Does anybody have a better suggestion how to check these lists for a given number?

Cheers

list python
4 Answers

try to use any function.

m = [[1,'O', 3], [4, 5, 6], [7, 8, 'X']]
while True:
    move = int(input('....'))
    if any(move in row for row in m):
        break
user_76876410

you could use a generator expression:

my_list = [[1,'O', 3], [4, 5, 6], [7, 8, 'X']]

move = 2
numbers = (e for l in my_list for e in l)

if move not in numbers:
    move = int(input("Number already taken. Pick another"))

a more compact version:

numbers = (e for l in my_list for e in l)
move = 2 if 2 in numbers else int(input("Number already taken. Pick another"))
user_31615750

Given your environment:

target = 2
list_of_lists = [[1,'O', 3], [4, 5, 6], [7, 8, 'X']]

I would do something like that with a one-liner:

True in [target in element for element in list_of_lists]
user_13920080

While Andrea's answer is more concise and clean, the answer to why your code does not work is because you are comparing two variables with the not in comparator which expect a list on the right hand. More info on that here: https://docs.python.org/3/reference/expressions.html#membership-test-operations

So to solve it, either remove the inner loop and compare the move with the inner lists, or use an equality comparator instead. Both options are below:

board = [[1,'O', 3], [4, 5, 6], [7, 8, 'X']]

move = 2
for i in range(3):
  if move not in board[i]:
    move = int(input("1: Number already taken. Pick another"))

for i in range(3):
    for j in range(3):
        if move == board[i][j]:
            move = int(input("2: Number already taken. Pick another"))
user_54784620
Related