python difflib print only matches part between two strings

I am totally new with python, and I need some help about difflib. I tried read the documentation, but for me is not easy to understand the docs.

I would like compare two strings, and I want the output is only the matches prefix-part between two string (do not print the differences) .

Example:

t1 = "hello my name is Tom"
t2 = "hello his name is Sawyer"


expected output is: "hello "

I tried by following approaches, but the output is not what I want because it print the output as array and also print not only matches part:

#!/usr/bin/python

import difflib
t1 = "hello my name is Tom"
t2 = "hello his name is Sawyer"
seq = difflib.Differ()
seq = seq.compare(t1,t2)
print list(seq)


other example-2:

t1 = "20180628-153020"
t2 = "20180628-173020"


expected output printout:
"20180628-1"
and the suffix "3020" even both part of string matches the position and characters, it should be ignored.

Please help me.. thank you...

update 2018/07/02

I wrote a small code to get only similar part of prefix between two strings (without using takewhile as 1st answer from @Eugene), but I think the 2nd code written by @Eugene in the answer is more shorter and efficient than mine.
here is my code:

takewhile

def getprefix(s1, s2):
pref = ""
ls1 = list(s1)
ls2 = list(s2)
i=0
while i < len(ls1):
if ls1[i] not in ls2[i]:
return pref
pref += ls1[i]
i += 1


1 Answer
1

In [1]: from itertools import takewhile
In [2]: ''.join(a for (a, b) in takewhile(lambda (a, b): a == b, zip(t1, t2)))
Out[2]: '20180628-1'


Here we zip two strings together and iterate on them while their prefixes are equal.

Upd. Equivalent solution not using itertools:

itertools

result =
for a, b in zip(t1, t2):
if a != b:
break
result.append(a)
return ''.join(result)


wow!! superr!!! exactly what I need.Thank you, Sir! :)
– guete
Jun 28 at 15:40

@guete Then you might want to mark this answer as accepted ;)
– Eugene Primako
Jun 28 at 15:47

absolutely Sir! Thanks :)
– guete
Jun 28 at 15:49

btw @Eugene, what is other approaches if my live system don't have itertools? I also don't have access to add new modules to the system. any idea?.
– guete
Jun 29 at 9:06

@guete itertools is not a custom module but a part of standard python library. So I guess you can access it. Any way, you can replace takewhile with for (I'll update my answer)
– Eugene Primako
Jun 29 at 9:55

takewhile

for

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