Removing an element from a list based on a predicate

Question

I want to remove an element from list, such that the element contains \'X\' or \'N\'. I have to apply for a large genome. Here is an example:

Answer 1

Another not fastest way but I think it reads nicely

>>> [x for x in ['AAT','XAC','ANT','TTA'] if not any(y in x for y in "XN")]
['AAT', 'TTA']

>>> [x for x in ['AAT','XAC','ANT','TTA'] if not set("XN")&set(x)]
['AAT', 'TTA']

This way will be faster for long codons (assuming there is some repetition)

codon = ['AAT','XAC','ANT','TTA']
def pred(s,memo={}):
    if s not in memo:
        memo[s]=not any(y in s for y in "XN")
    return memo[s]

print filter(pred,codon)

Here is the method suggested by James Brooks, you'd have to test to see which is faster for your data

codon = ['AAT','XAC','ANT','TTA']
def pred(s,memo={}):
    if s not in memo:
        memo[s]= not set("XN")&set(s)
    return memo[s]

print filter(pred,codon)

For this sample codon, the version using sets is about 10% slower