Extract substring between two characters - python DataFrame

Question

What is the meaning of string locator ', \s*([^\.]*)\s*\.' =?

I have a dataframe identical to Extract sub-string between 2 special characters from one column of Pandas DataFrame

and want to extract the substring located between "," and ".". Thanks to the post answer, a way would be as below:

In [157]: df['Title'] = df.Name.str.extract(r',\s*([^\.]*)\s*\.', expand=False)

In [158]: df
Out[158]:
                   Name   Title
0        Jim, Mr. Jones      Mr
1     Sara, Miss. Baker    Miss
2     Leila, Mrs. Jacob     Mrs
3  Ramu, Master. Kuttan  Master

Although I see the outcome being correct, what is the meaning of ',\s*([^\.]*)\s*\.'? In particular, what is the meaning of '*' and '\'?

@JustBaron. The first = symbol was part of the question mark, not the expression =) — Mad Physicist
– Mad Physicist, Commented Sep 8, 2018 at 14:39
Possible duplicate of Reference - What does this regex mean? — Paolo
– Paolo, Commented Sep 8, 2018 at 14:49

Dani Mesejo · Accepted Answer · 2018-09-08 14:52:06Z

2

It means the following, match:

a , (comma)
followed by \s* zero or more whitespaces characters (tab, spaces, etc)
followed by ([^\.])* zero or more characters that are not a . (dot)
followed by \s* zero or more whitespaces characters
followed by a \. (dot)

You can find more about regex in here.

UPDATE

As @UnbearableLightness mentioned the character \ is redundant inside a character set to escape the . (dot). A character set is anything defined between [].

edited Sep 8, 2018 at 14:52

answered Sep 8, 2018 at 14:41

Dani Mesejo

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2 Comments

Paolo Over a year ago

The \ in the character set is escaping the dot, which is of course redundant. A \ will still be matched by the expression.

Cuisilopez Over a year ago

Thanks a lot for the help! :)

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