在python中的字符周围拆分字符串

Question

Hey guys I have seen on here answers to how to split strings at a specified character and that's pretty simple. What I need to know is how to split strings between 2 characters

ie splitting for character strings beginning with M and ending in Z RERTCRPVNMVRNSRRTNSKSRSRHRZGRCRCGRHWVRNFDNPFISRYRRSZTSFFIFTVKFLSSYGLKKRKIKRTTVKVQGSTIMSLLNTZLN

into RERTCRPVN MVRNSRRTNSKSRSRHRZ GRCRCGRHWVRNFDNPFISRYRRSZTSFFIFTVKFLSSYGLKKRKIKRTTVKVQGSTI MSLLNTZ LN

and later only keeping those desired.

I might be able to form some kind of weird loop to do this like

NET=Aminos.split('M')
LIST=[]
rock= int(0)
while LIST[rock]!= 'M' and LIST[rock]!= '':
    LIST.append('M' + NET[rock])
    rock=rock + 1
    other=other+1
print(LIST)

but in this given example I get the index out of range error.

This sort of thing seems rather tedious as well because I would have to break LIST apart after each Z with a split and try to concatenate 'Z' to the end of each.

Does anyone know of a way of doing this more efficiently?

Answer 1

You can use regular expressions to extract all strings beginning with M and ending with Z from a string:

>>> re.findall('M.*?Z', "RERTCRPVNMVRNSRRTNSKSRSRHRZGRCRCGRHWVRNFDNPFISRYRRSZTSFFIFTVKFLSSYGLKKRKIKRTTVKVQGSTIMSLLNTZLN")
['MVRNSRRTNSKSRSRHRZ', 'MSLLNTZ']

Or, if you want to keep the strings in between as well:

>>> re.split('(M.*?Z)', "RERTCRPVNMVRNSRRTNSKSRSRHRZGRCRCGRHWVRNFDNPFISRYRRSZTSFFIFTVKFLSSYGLKKRKIKRTTVKVQGSTIMSLLNTZLN")
['RERTCRPVN', 'MVRNSRRTNSKSRSRHRZ', 'GRCRCGRHWVRNFDNPFISRYRRSZTSFFIFTVKFLSSYGLKKRKIKRTTVKVQGSTI', 'MSLLNTZ', 'LN']

Answer 2

This sounds like something for re.split :

ie:

import re
ex = re.compile("M.*Z")

splitted = re.split(ex, <some input string>)

Edit: Updated per Tim Heap, as I misinterpreted "beginning with M and ending in Z" as occurring at word boundaries.

Edit 2: After @Cairnarvon's feedback, here is an example that works (surprisingly, re.split doesn't accept the result of re.compile , you must pass in the regex as a string:

>>> s = "RERTCRPVNMVRNSRRTNSKSRSRHRZGRCRCGRHWVRNFDNPFISRYRRSZTSFFIFTVKFLSSYGLKKRKIKRTTVKVQGSTIMSLLNTZLN"
>>> ex = re.compile("(M.*?Z)")
>>> re.split(s, ex)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/re.py", line 167, in split
    return _compile(pattern, flags).split(string, maxsplit)
TypeError: expected string or buffer
>>> re.split("M.*Z", s)
['RERTCRPVN', 'LN']