Python字符串由多个定界符分隔

Question

Given a string: s = FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE

The delimiting characters are P , Q , D and E

I want to be able to split the string on these characters.

Based on: Is it possible to split a string on multiple delimiters in order?

I have the following

def splits(s,seps):
    l,_,r = s.partition(seps[0])
    if len(seps) == 1:
        return [l,r]
    return [l] + splits(r,seps[1:])

seps = ['P', 'D', 'Q', 'E']

sequences = splits(s, seps)

This gives me:

['FFFFRRFFFFFFF',
 'PRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLF',
 'RRFRRFFFFFFFFR',
 '',
 'E']

As we can see the second entry has many P .

I want is the occurrence of characters between the last set of P , not the first occurrence (ie, RFFFFFFFLF ).

Also, the order of occurrence of the delimiting characters is not fixed.

Looking for solutions/hints on how to achieve this?

Update: Desired output, all set of strings between these delimiters (similar to the one shown) but adhering to the condition of the last occurrence as above

Update2: Expected output

['FFFFRRFFFFFFF',
 'RFFFFFFFLF',   # << this is where the output differs
 'RRFRRFFFFFFFFR',
 '',
 '']   # << the last E is 2 consecutive E with no other letters, hence should be empty

Answer 1

Sounds like you want to split at sequence from first character appearance until the last.

([PDQE])(?:.*\1)?

• ([PDQE]) captures one of the characters in class
• (?:.*\\1)? optionally match any amount of characters until last occurence of captured .

Have a try with split pattern at regex101 and a PHP Demo at 3v4l.org (should be similar in Python).

Answer 2

import re

s = "FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE"

def get_sequences(s):
    seen_delimiters = {c: ('', None) for c in 'PDQE'}
    order = 0
    for g in re.finditer(r'(.*?)([PDQE]|\Z)', s):
        if g[2]:
            if seen_delimiters[g[2][0]][1] == None:
                seen_delimiters[g[2][0]] = (g[1], order)
                order += 1
    return seen_delimiters

for k, (seq, order) in get_sequences(s).items():
    print('{}: order: {} seq: {}'.format(k, order, seq))

Prints:

P: order: 0 seq: FFFFRRFFFFFFF
D: order: 1 seq: RFFFFFFFLF
Q: order: 2 seq: RRFRRFFFFFFFFR
E: order: 3 seq: 

Update (for print sequences and delimiters enclosing):

import re
s = "FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE"
for g in re.finditer(r'(.*?)([PDQE]+|\Z)', s):
    print(g[1], g[2])

Prints:

FFFFRRFFFFFFF PP
RRRRRRLLRLLRLLL PP
F PP
L PP
L PP
LF PP
FF P
FLR P
FFRRLLR P
F P
RFFFFFFFLF D
RRFRRFFFFFFFFR QEE

Answer 3

Use re.split with a character class [PQDE] :

import re

s = 'FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE'    
sequences = re.split(r'[PQDE]', s)
print(sequences)

Output:

['FFFFRRFFFFFFF', '', 'RRRRRRLLRLLRLLL', '', 'F', '', 'L', '', 'L', '', 'LF', '', 'FF', 'FLR', 'FFRRLLR', 'F', 'RFFFFFFFLF', 'RRFRRFFFFFFFFR', '', '', '']

---

If you want to split on 1 or more delimiter:

import re

s = 'FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE'    
sequences = re.split(r'[PQDE]+', s)
print(sequences)

Output:

['FFFFRRFFFFFFF', 'RRRRRRLLRLLRLLL', 'F', 'L', 'L', 'LF', 'FF', 'FLR', 'FFRRLLR', 'F', 'RFFFFFFFLF', 'RRFRRFFFFFFFFR', '']

---

If you want to capture the delimiters:

import re

s = 'FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE'    
sequences = re.split(r'([PQDE])', s)
print(sequences)

Output:

['FFFFRRFFFFFFF', 'P', '', 'P', 'RRRRRRLLRLLRLLL', 'P', '', 'P', 'F', 'P', '', 'P', 'L', 'P', '', 'P', 'L', 'P', '', 'P', 'LF', 'P', '', 'P', 'FF', 'P', 'FLR', 'P', 'FFRRLLR', 'P', 'F', 'P', 'RFFFFFFFLF', 'D', 'RRFRRFFFFFFFFR', 'Q', '', 'E', '', 'E', '']

Answer 4

This solution is iterating the delimiters one by one, so you can control the order you want to apply each one of them:

s = 'FFFFRRFFFFFFFPPRRRRRRLLRLLRLLLPPFPPLPPLPPLFPPFFPFLRPFFRRLLRPFPRFFFFFFFLFDRRFRRFFFFFFFFRQEE'
spliters='PDQE'
for sp in spliters:
    if type(s) is str:
        s = s.split(sp)
    else: #type is list
        s=[x.split(sp) for x in s]
        s = [item for sublist in s for item in sublist if item != ''] #flatten the list

output:

['FFFFRRFFFFFFF',
 'RRRRRRLLRLLRLLL',
 'F',
 'L',
 'L',
 'LF',
 'FF',
 'FLR',
 'FFRRLLR',
 'F',
 'RFFFFFFFLF',
 'RRFRRFFFFFFFFR']