Python正则表达式“负”模式匹配

Question

I am working on a large batch of text strings, trying to match date times and convert them to MM-DD-YYYY format using strptime() function.

However, there are some 5-digit serial number appeared in the texts (eg, 90481) that have mislead my .findall() function to treat them as date times. How can I avoid them by including a ^() type of condition to exclude them?

What them have in common is that they are all 5-digit, so I have tried ^(?!\\d{5}) but it didn't turn out well. What's the best way to tackle this set of number?

Thank you.

Note1: I have read this post , but can't seem to get it.

Note2: about date format someone have asked in the comment section

There are many date formats in the data frame I am working on, for example:

 05/10/2001; 05/10/01; 5/10/09; 6/2/01 May-10-2001; May 10, 2010; March 25, 2001; Mar. 25, 2001; Mar 25 2001; 25 Mar 2001; 25 March 2001; 25 Mar. 2001; 25 March, 2001 Mar 25th, 2001; Mar 25th, 2001; Mar 12nd, 2001 Feb 2001; Sep 2001; Oct 2001 5/2001; 11/2001 2001; 2015 

So I have a rather long .findall(r' ') function, but the main point is to avoid those 5-digit serial number from be selected.

Sincerely,

Answer 1

You could use \\b in your regex, to avoid that a match is found halfway a number with more digits. Place one at the start and one at the end, and make sure they are not included in the scope of the | (OR) operation by wrapping the rest in a non-capture group.

I removed some months to keep it short:

\b(?:\d{1,2}\/\d{1,2}\/\d{2,4}|(?:Jan|Feb|Mar|Apr|   |Nov|Dec)[a-z]*-\d{2}-\d{2,4})\b