how to remove negetive value in nested list

Question

I’m new to Python programming and I’ve written the following code:

y = [[-1, -2, 4, -3, 5], [2, 1, -6], [-7, -8, 0], [-5, 0, -1]]
for row in y:
    for col in row:
        if col < 0:
            row.remove(col)
print(y)

I want to remove elements with negative values from the nested list. However, when two negative values are adjacent, the code doesn’t remove the second value. What modifications can I make to ensure the removal of all negative values?

Asked By: saraafr

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Source

Answer 1

[[item for item in arr if item >= 0] for arr in y]

Answered By: ksha

Answer 2

You may never remove items form a list while iterating it, you’d keep the ones you need, the positive ones

y = [[col for col in row if col>=0] for row in y]

Answered By: azro

Answer 3

You can use filter and lambda function:


    y = [[-1, -2, 4, -3, 5], [2, 1, -6], [-7, -8, 0], [-5, 0, -1]]

    y = [list(filter(lambda col: col >= 0, row)) for row in y]

    print(y)

Answered By: ariankazemi

Answer 4

You can use a combination of map and list comprehensions.

Here’s an example:

y = [[-1, -2, 4, -3, 5], [2, 1, -6], [-7, -8, 0], [-5, 0, -1]]
y = list(map(lambda row: [col for col in row if col >= 0], y))
print(y)

Output:

[[4, 5], [2, 1], [0], [0]]

Answered By: XM01 – stands with Palestine

how to remove negetive value in nested list

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