How to remove certain lists from a list of lists using python?

Question

I can not figure out why my code does not filter out lists from a predefined list. I am trying to remove specific list using the following code.

data = [[1,1,1],[1,1,2],[1,2,1],[1,2,2],[2,1,1],[2,1,2],[2,2,1],[2,2,2]]
data = [x for x in data if x[0] != 1 and x[1] != 1]

print data

My result:

data = [[2, 2, 1], [2, 2, 2]]

Expected result:

data = [[1,2,1],[1,2,2],[2,1,1],[2,1,2],[2,2,1],[2,2,2]]

In [1, 2, 1], x[0] == 1 so it automatically disqualifies it. And so on and so forth... — Joel Cornett
– Joel Cornett, Commented Oct 26, 2012 at 22:42
To match the way you're thinking of the problem, use: if not (x[0] == 1 and x[1] == 1) — alexis
– alexis, Commented Oct 26, 2012 at 22:44
You're welcome. Note that it's logically equivalent to using or, as the other guys suggested: because not (A and B) == (not A) or (not B) — alexis
– alexis, Commented Oct 26, 2012 at 22:50
Turned the above into an answer, if you feel like accepting it... — alexis
– alexis, Commented Oct 26, 2012 at 22:58

gefei · Accepted Answer · 2012-10-26 22:35:27Z

3

and is wrong, use or

data = [x for x in data if x[0] != 1 or x[1] != 1]

answered Oct 26, 2012 at 22:35

gefei

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Amber · Accepted Answer · 2012-10-26 22:35:43Z

2

and is only true if both sides are true values. Perhaps you want...

data = [x for x in data if x[0] != 1 or x[1] != 1]

answered Oct 26, 2012 at 22:35

Amber

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Comments

anijhaw · Accepted Answer · 2012-10-27 18:58:17Z

0

I think this is what the OP wants.

data = [[1,1,1],[1,1,2],[1,2,1],[1,2,2],[2,1,1],[2,1,2],[2,2,1],[2,2,2]]

data = [x for x in data if x[:2] != [1,1]]
print data

data = [x for x in data if ((x[0],x[1]) != (1,1))]   
print data

edited Oct 27, 2012 at 18:58

answered Oct 26, 2012 at 22:45

anijhaw

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2 Comments

masterial Over a year ago

Good one as well! But this is not so well adaptable if I would want to filter by 1st and 3rd value of list instead.

anijhaw Over a year ago

How about the second solution.

alexis · Accepted Answer · 2012-10-26 22:57:47Z

0

You had a small logic error. To match the way you're thinking of the problem, use:

if not (x[0] == 1 and x[1] == 1)

Note that this is logically equivalent to using or, as the other guys suggested:

not (A and B) == (not A) or (not B)

answered Oct 26, 2012 at 22:57

alexis

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Comments

Tyler2P · Accepted Answer · 2021-10-23 00:56:42Z

0

In your code "or" should be used in the place of "and". And "and" is used if u want to execute both the values. Example:

data = [x for x in data if x[0] != 1 or x[1] != 1]

edited Oct 23, 2021 at 0:56

Tyler2P

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answered Oct 22, 2021 at 16:44

Meghana Chippada

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