Python Regex-根据开头和结尾捕获句子

Question

I'm fairly new to python, but I'm attempting to write a program that will capture a sentence out of a string, based of the beginning and ending of the sentence.

For example if my string was

description = "11:26:16 ENTRY 'Insert Imaginative Description of a person' 11:29:17 EXIT 'Insert The Description of the Same Person'"

I know how to do the regex to detect the date stamp and the word entry. I'd use:

re.search(r'\d{2}:\d{2}:\d{2} ENTRY', description)

Which would of course tell me that there was one entry at that position, but how would I make the regex capture the date stamp, entry and the following sentence, but leave out the EXIT log?

Answer 1

You may try this.

re.search(r'\b(\d{2}:\d{2}:\d{2}(?:\.\d{3})?) ENTRY', description)

Use re.findall if you want to do a global match since re.search would return only the first match.

Example:

>>> import re
>>> description = "11:26:16 ENTRY 'Insert Imaginative Description of a person' 11:29:17 EXIT 'Insert The Description of the Same Person'"
>>> re.search(r'\b(\d{2}:\d{2}:\d{2}(?:\.\d{3})?) ENTRY', description).group(1)
'11:26:16'

To get also the log after the ENTRY .

>>> re.search(r"\b(\d{2}:\d{2}:\d{2}(?:\.\d{3})?) ENTRY '([^']*)'", description).group(1)
'11:26:16'
>>> re.search(r"\b(\d{2}:\d{2}:\d{2}(?:\.\d{3})?) ENTRY '([^']*)'", description).group(2)
'Insert Imaginative Description of a person'
>>> re.search(r"\b(\d{2}:\d{2}:\d{2}(?:\.\d{3})?) ENTRY '([^']*)'", description).group()
"11:26:16 ENTRY 'Insert Imaginative Description of a person'"

Answer 2

Add in brackets ( ) around the pattern you want to match to get groups returned for them, plus your pattern doesn't actually match your example - the pattern expects a . and three digits. You can make these optional like this:

match = re.search(r'(\d{2}:\d{2}:\d{2}(\.\d{3})?) ENTRY', description)
if match:
    print match.group(1)

To capture the sentence, extend the pattern like this:

match = re.search(r'(\d{2}:\d{2}:\d{2}(\.\d{3})?) ENTRY \'([^\']+)\'', description)
if match:
    print match.group(1), match.group(3)

Note the sentence is in group 3 because the option three digits are group 2. Output is:

11:26:16 Insert Imaginative Description of a person

Because the pattern must match the ' ' around the sentence, these are preceded with backslash . Another way of doing this would be to use " " around the whole pattern, in whcih case the ' do not need backslash before them.