I have a substring 'G^ATTC'
and I want to find the number of time it occurs in a string like 'ATCGCGATTC'
but I cannot because of '^'
.
I used re.findall
, but the result is always 0
.
This is because in Regex, the "^" character means "the start of the line." Related to this, "$" means "the end of a line"
So, when it's searching for "G^ATTC", it would never match anything, because you're saying the "G" comes before the start of the line (which doesn't even make sense).
The way to fix your regex is to include a "\" to escape the "^". This tells regex to treat the "^" as a character instead of the start of the line.
So, change it to "G\^ATTC"
maybe something like this:
import re
txt = "ATCGCG1ATTCAAAAAAAAAAAAAG4ATTC"
substring = 'G^ATTC'
x = re.findall(substring.replace('^','.'), txt) # ['G1ATTC', 'G4ATTC']
print ("pattern {} occurs {} times".format(substring,len(x)))
output:
pattern G^ATTC occurs 2 times
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