Python-Pandas:将数字从列中提取到新列中 [英] Python - Pandas: extract a number from column into new column

问题描述

我一直在用python处理熊猫来提取信息.我的数据框的一栏中有以下标题:

I've been working a lot with pandas in python to extract information. I have the following titles in one column of my dataframe:

   0
In & Out (1997)
Simple Plan, A (1998)
Retro Puppetmaster (1999)
Paralyzing Fear: The Story of Polio in America, A (1998)
Old Man and the Sea, The (1958)
Body Shots (1999)
Coogan's Bluff (1968)
Seven Samurai (The Magnificent Seven) (Shichinin no samurai) (1954)
Search for One-eye Jimmy, The (1996)
Funhouse, The (1981)

我想把那些标题的岁月放进新的一列.我遇到的问题是，如果我在定界符'('上进行拆分，如您在第8行上看到的那样，它就在那里拆分了.那么我如何在(yyyy)拆分以与该年组成一个新列看起来像这样?

I'd like to take the years of those titles and put into a new column. The issue I'm running into is if I do the split on '(' as the delimiter, as you see on row 8, it's split there. So how do I split at the (yyyy) to form a new column with that year to look like this?

     0                 1
In & Out              1997
Simple Plan, A        1998
Retro Puppetmaster    1999 
Paralyzing Fear:...   1998
Old Man and the S...  1958
Body Shots            1999
Coogan's Bluff        1968 
Seven Samurai (T...   1954
Search for One-ey...  1996
Funhouse, The         1981

推荐答案

您可以使用expand:

You can use expand:

df['year'] = df.iloc[:,0].str.extract('\((\d{4})\)'',expand=False)

df
Out[381]: 
                                                   0  year
0                                    In & Out (1997)  1997
1                              Simple Plan, A (1998)  1998
2                          Retro Puppetmaster (1999)  1999
3  Paralyzing Fear: The Story of Polio in America...  1998
4                    Old Man and the Sea, The (1958)  1958
5                                  Body Shots (1999)  1999
6                              Coogan's Bluff (1968)  1968
7  Seven Samurai (The Magnificent Seven) (Shichin...  1954
8               Search for One-eye Jimmy, The (1996)  1996
9                               Funhouse, The (1981)  1981

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