How to get a list item that is in another list to delete it on the first in Python 3

Question

I'm new to Python, and I'm trying to make a sudoku solver. Now, I need to check if a number in a candidates list is in another list, and if it is, delete it from the candidates list.

line1 = [6,6,6,6]

def checkline(x):
candidates = [1,2,3,4]

if any(number in x for number in candidates):
    crap = int in x and candidates
    print(crap)
    candidates.remove(crap)
    print ("Works")
    print(candidates)

x = line1. I want "crap" to be the common number. How do I do it?

Answer 1

与其从列表中删除它，不如考虑使用过滤后的项目创建一个新列表：

candidates = [i for i in candidates if i not in line1]

Answer 2

I don't exactly understand the logic in your code but here is how you can "check if a number in a candidates list is in another list, and if it is, delete it from the candidates list":

candidates = [1, 2, 3, 4]
another_list = [1, 4, 5, 6, 7 ,8, 9]

for index, candidate in enumerate(candidates):
    if candidate in another_list:
        del candidates[index]

After running the code above, candidates will be [2, 3] .

For completeness (from a learning perspective), the code above can also be written without enumerate , like so:

candidates = [1, 2, 3, 4]
another_list = [1, 4, 5, 6, 7 ,8, 9]

for candidate in candidates:
    if candidate in another_list:
        candidates.remove(candidate)

This is not the best way of approaching this problem but I thought it'll be easier for you to understand what the logic required is then you should re-think how you're solving this. At the least, using Python's list comprehensions (instead of the for statements above) would be of great help here:

candidates = [1, 2, 3, 4]
another_list = [1, 4, 5, 6, 7 ,8, 9]
candidates = [candidate for candidate in candidates if candidate not in another_list]

Is this helpful?

Answer 3

Pehaps, you need something like this:

def checkline(line1,candidates):
    buf=[]
    for crap in candidates:
        if crap not in line1:
           buf.append(crap)
    return buf

candidates=checkline(line1,candidates)