pa = re.compile("(?P<A>\w+)(?):\[(?P<B>\d+):(?P<C>\d+)\]|[(?P<D>\d+)]")
I want to know the meaning of the regular expression above.
I understood the two (?P<A>\w+) and (?P<D>\d+).
I don't understand the middle part where I was blocked.
Center (?:\[(?P<B>\d+):(?P<C>\d+)\]|(?P<D>\d+)\]?
What does ?:\ mean here?And what does the last word mean?
[ ]Should I put this in before wrapping it up...
I think it's related to the Python list indexer. Test results here
my_list[3]
# # Match 1: my_list[3]
# # Group A: my_list
# # Group D: 3
my_list[2:5]
# # Match 1: my_list[2:5]
# # Group A: my_list
# # Group B: 2
# # Group C: 5
Indexed as shown in .
(?P<A>\w+) means that all characters are grouped into Group A
(?:\[(?P<B>\d+):(?P<C>\d+)\]|\[(?P<D>\d+)]) when you split or
\[(?P<B>\d+):(?P<C>\d+)\] and \[(?P<D>\d+)\]
It seems that you want to divide the group into B, C, or D, depending on whether it is a colon in square brackets.
The last ? I really don't know.
I guess it's for error detection.
my_list[3]error
# # Match 1: my_list[3]
# # Group A: my_list
# # Group D: 3
# # Match 2: error
# # Group A: error
As you can see, it gets caught in Match 2, but if you remove the ? at the end, it doesn't get caught.
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