Question

I have text line by line which contains many field name and their value seperated by : , if any line does not have any field value then that field would not exist in that line
for example

First line:
A:30 B: 40 TS:1/1/1990 22:22:22
Second line
A:30 TS:1/1/1990 22:22:22
third line
A:30 B: 40

But it is confirmed that at max 3 fields are possible in single line and their name will be A,B,TS.
while writing python script for this, i am facing below issues:
1) I have to extract from each line which are the field exist and what are their values
2) Field value of field TS also have seperator ‘ ‘(SPACE).so unable retrieve full value of TS(1/1/1990 22:22:22)

Output valueshould be extracted like that

First LIne:
A=30
 B=40
 TS=1/1/1990 22:22:22

Second Line:
A=30

 TS=1/1/1990 22:22:22

Third Line
A=30
 B=40

Please help me in solving this issue.

Answer 1

import re
a = ["A:30 B: 40 TS:1/1/1990 22:22:22", "A:30 TS:1/1/1990 22:22:22", "A:30 B: 40"]
regex = re.compile(r"^\s*(?:(A)\s*:\s*(\d+))?\s*(?:(B)\s*:\s*(\d+))?\s*(?:(TS)\s*:\s*(.*))?$")
for item in a:
    matches = regex.search(item).groups()
    print {k:v for k,v in zip(matches[::2], matches[1::2]) if k}

will output

{'A': '30', 'B': '40', 'TS': '1/1/1990 22:22:22'}
{'A': '30', 'TS': '1/1/1990 22:22:22'}
{'A': '30', 'B': '40'}

Explanation of the regex:

^\s*      # match start of string, optional whitespace
(?:       # match the following (optionally, see below)
 (A)      # identifier A --> backreference 1
 \s*:\s*  # optional whitespace, :, optional whitespace
 (\d+)    # any number --> backreference 2
)?        # end of optional group
\s*       # optional whitespace
(?:(B)\s*:\s*(\d+))?\s*  # same with identifier B and number --> backrefs 3 and 4
(?:(TS)\s*:\s*(.*))?     # same with id. TS and anything that follows --> 5 and 6
$         # end of string