正则表达式-字符串不包含特定字符

Question

I want a regular expression that would check if a string contains any character apart from "A" , "G", "C" , "U" e the string would be like ggggugcccgcuagagagacagu

i want regex to check if it containns only these , it is not case sensitive.

what i tried

match= re.match(r'[^GaAgUuCc]',seq2)

It is to find non RNA characters in a RNA sequence

Answer 1

Use re.search instead:

>>> re.search(r'[^GAUC]', 'acg', re.I)
>>> re.search(r'[^GAUC]', 'acgf', re.I)
<_sre.SRE_Match object at 0x7f1b6a9e32a0>

re.I makes the regex case-insensitive.

A faster way to do it would be to use sets to check if the set of characters is a subset of your allowed characters:

>>> set('acg'.upper()) <= set('GAUC')
True
>>> set('acgs'.upper()) <= set('GAUC')
False

Answer 2

You need to use a quantifier with your regex to match more characters: -

>>> match = re.search("[^GAUC]+","ggggugcccgcuagrrragagacagu", re.I)
>>> match
9: <_sre.SRE_Match object at 0x01BCA8A8>
>>> match.group()
10: 'rrr'

Answer 3

You should use re.search() or re.findall() rather than re.match() :

In [9]: seq2 = 'ggggugcccQgcuagagaZgacagu'

In [10]: re.findall(r'[^GaAgUuCc]',seq2)
Out[10]: ['Q', 'Z']