Python 从 Pandas 中的字符串中提取 int
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Extract int from string in Pandas
提问by user5739619
Lets say I have a dataframe dfas
比方说，我有一个数据帧df作为
A B
1 V2
3 W42
1 S03
2 T02
3 U71
I want to have a new column (either at it the end of dfor replace column Bwith it, as it doesn't matter) that only extracts the int from the column B. That is I want column Cto look like
我想要一个新列（在它的末尾df或B用它替换列，因为它无关紧要）只从列中提取 int B。那是我希望列C看起来像
C
2
42
3
2
71
So if there is a 0 in front of the number, such as for 03, then I want to return 3 not 03
所以如果数字前面有0，比如03，那么我要返回3而不是03
How can I do this?
我怎样才能做到这一点？
采纳答案by Lokesh A. R.
You can convert to string and extract the integer using regular expressions.
您可以转换为字符串并使用正则表达式提取整数。
df['B'].str.extract('(\d+)').astype(int)
回答by Mike Graham
Assuming there is always exactly one leading letter
假设总是只有一个前导字母
df['B'] = df['B'].str[1:].astype(int)
回答by boesjes
I wrote a little loop to do this , as I didn't have my strings in a DataFrame, but in a list. This way, you can also add a little if statement to account for floats :
我写了一个小循环来做到这一点，因为我的字符串不在 DataFrame 中，而是在列表中。这样，您还可以添加一点 if 语句来说明浮动：
output= ''
input = 'whatever.007'
for letter in input :
try :
int(letter)
output += letter
except ValueError :
pass
if letter == '.' :
output += letter
output = float(output)
输出 = 浮点数（输出）
or you can int(output) if you like.
或者你可以 int(output) 如果你喜欢。
回答by Kohn1001
Preparing the DF to have the same one as yours:
准备与您相同的 DF：
df = pd.DataFrame({'A': [1, 3, 1, 2, 3], 'B' : ['V2', 'W42', 'S03', 'T02', 'U71']})
df.head()
Now Manipulate it to get your desired outcome:
现在操纵它以获得您想要的结果：
df['C'] = df['B'].apply(lambda x: re.search(r'\d+', x).group())
df.head()
A B C
0 1 V2 2
1 3 W42 42
2 1 S03 03
3 2 T02 02
4 3 U71 71
