将长字符串中的子字符串切成python中的列表

Question

In python I have long string like (of which I removed all breaks)

stringA = 'abcdefkey:12/eas9ghijklkey:43/e3mnop'

What I want to do is to search this string for all occurrences of "key:" , then extract the "values" following "key:" . One further complication for me is that I don't know how long these values belonging to key are (eg key:12/eas9 and key:43/e3 ). All I do know is that they do have to end with a digit whereas the rest of the string does not contain any digits.

This is why my idea was to slice from the indices of key plus the next say 10 characters (eg key:12/eas9g ) and then work backward until isdigit() is false.

I tried to split my initial string (that did contain breaks):

stringA_split = re.split("\n", stringA)

for linex in stringA_split:
  index_start = linex.rfind("key:")
  index_end = index_start + 8
  print(linex[index_start:index_end]
  #then work backward

However, inserting line breaks does not help in any way as they are meaningless from a pdf-to-txt conversion.

How would I then solve this (eg as a start with getting all indices of '"key:"' and slice this to a list)?

Answer 1

I'm not 100% sure I understand your definition of what defines a value, but I think this will get you what you described

import re
stringA = 'abcdefkey:12/eas9ghijklkey:43/e3mnop'
for v in stringA.split('key:'):
    ma = re.match(r'(\d+\/.*\d+)', v)
    if ma:
        print ma.group(1)

This returns:

12/eas9
43/e3

Answer 2

You can apply just one RE that gets all the keys into an array of tuples:

import re
p=re.compile('key\:(\d+)\/([^\d]+\d)')
ret=p.findall(stringA)

After the execution, you have:

ret 
[('12', 'eas9'), ('43', 'e3')]

Answer 3

import re

>>> re.findall('key:(\d+[^\d]+[\d])', stringA)
['12/eas9', '43/e3']

\\d+ # One or more digits.

[^\\d]+ # Everything except a digit (equivalent to [\\D] ).

[\\d] # The final digit

(\\d+[^\\d]+[\\d]) # The group of the expression above

'key:(\\d+[^\\d]+[\\d])' # 'key:' followed by the group expression

If you want key: in your result:

>>> re.findall('(key:\d+[^\d]+[\d])', stringA)
['key:12/eas9', 'key:43/e3']

Answer 4

edit: a better answer was posted above. I misread the original question when proposing to reverse here, which really wasn't necessary. Good luck!

If you know that the format is always key:, what if you reversed the string and rex for :yek? You'd isolate all keys and then can reverse them back

import re
# \w is alphanumeric, you may want to add some symbols
rex = re.compile("\w*:yek")

word = 'abcdefkey:12/eas9ghijklkey:43/e3mnop'
matches = re.findall(rex, word[::-1])
matches = [match[::-1] for match in matches]