从 python 中的字符串中提取数字

Question

I am trying to extract only area numbers from a column in pandas dataframe: 568 sq mi (1,471 km2) here I only want 568 the space between the number and sq is unbreakable space.

Answer 1

you can probably do this

df[col].apply(lambda x:x[:3])

this will extract the starting number for the whole column, change the df with your data frame name and col with your column name

Answer 2

So try using regex on the string.

Eg:

import re
str = "568.78 sq mi (1,471 km2)"
num = re.findall(r"[0-9]+", str)
print(num[0])

Output:

568.78

Since its on the columns of dataframe try something like this.

def fmt(row):
   number = re.findall(r"[0-9,.]+",row)
   return number[0]

numbers = list(map(fmt,df[col]))
df['fmt area'] = numbers

Think this should work.

Answer 3

You can use the.str method and use extract and pass regular expression pattern.

import pandas as pd
df = pd.DataFrame({"Area":["568 sq mi (1,471 km2)"]})

df["area changed"] = df.Area.str.extract(r"(\d+ \w+)")