Using Python, how can I check whether 3 consecutive chars within a string (A) are also contained in another string (B)? Is there any built-in function in Python?
EXAMPLE:
A = FatRadio
B = fradio
Assuming that I have defined a threshold of 3, the python script should return true as there are three consecutive characters in B which are also included in A (note that this is the case for 4 and 5 consecutive characters as well).
How about this?
char_count = 3 # Or whatever you want
if len(A) >= char_count and len(B) >= char_count :
for i in range(0, len(A) - char_count + 1):
some_chars = A[i:i+char_count]
if some_chars in B:
# Huray!
A = "abcdefghijk" and B = "zzijk". Even though they share a triplet the code doesn't find it.
You can use the difflib module:
import difflib
def have_common_triplet(a, b):
matcher = difflib.SequenceMatcher(None, a, b)
return max(size for _,_,size in matcher.get_matching_blocks()) >= 3
Result:
>>> have_common_triplet("FatRadio", "fradio")
True
Note however that SequenceMatcher does much more than finding the first common triplet, hence it could take significant more time than a naive approach. A simpler solution could be:
def have_common_group(a, b, size=3):
first_indeces = range(len(a) - len(a) % size)
second_indeces = range(len(b) - len(b) % size)
seqs = {b[i:i+size] for i in second_indeces}
return any(a[i:i+size] in seqs for i in first_indeces)
Which should perform better, especially when the match is at the beginning of the string.
I don't know about any built-in function for this, so I guess the most simple implementation would be something like this:
a = 'abcdefgh'
b = 'foofoofooabcfoo'
for i in range(0,len(a)-3):
if a[i:i+3] in b:
print 'then true!'
Which could be shorten to:
search_results = [i for in range(0,len(a)-3) if a[i:i+3] in b]
