如何将自定义正则表达式 function 应用于 dataframe Python 中的列

Question

I have been searching for the past two days on this site and google to and I can not figure this out. I have a dataframe with 4 columns. I feel like it is something so easy that I am missing. Here is my function:

  def zip_code(zip):
     if re.match('^[0-9]{5}(?:-[0-9]{4})?$',zip):
    #zip = 5
        return zip
    else:
        return ''

my customer information

   customer_info = (['John', 'Summers', '22960', '434-305-6600'], 
            ['Josh', 'Williams', '40143', '270-555-1544'],
            ['Jim', 'Roberson', '21801','555-555-5555'],
            ['John', 'Adams', '223211143', '4444444444']

This is my various attempts to make it work

   dataframe = pd.DataFrame(customer_info,columns = ['First','Last','Zip','Phone'])

   #dataframe['Zip'] = dataframe['Zip'].apply(zip_code())
   #dataframe['Zip'] = dataframe['Zip'].apply(zip_code(dataframe['Zip']))

   #dataframe['Zip'] = dataframe['Zip'].apply(lambda x: re.match('^[0-9]{5}(?:-[0-9]{4})?$',x))

   #dataframe.Zip.apply(lambda x: zip_code(x))
   #dataframe['Zip'].apply(zip_code)

   print(dataframe)
   zipcode = zip_code('22960')
   print(zipcode)

What I am trying to do is run a check on the zip code column 'Zip'. If it is a zip code that matches ##### or #####-#### it will return the zip code. Other wise it will return an empty space. I have tested the zip code function and it works as expected. However, I can no figure out how to pass the entire Zip column through the zip_code function. Everytime I type zip_code() it asks for variable. Pretty much all of the commented out lines are lines that I found browsing this site, but it did not help me. Thank you for any help you can provide!

Answer 1

This could work

import pandas as pd
customer_info = (['John', 'Summers', '22960', '434-305-6600'], 
            ['Josh', 'Williams', '40143', '270-555-1544'],
            ['Jim', 'Roberson', '21801','555-555-5555'],
            ['John', 'Adams', '223211143', '4444444444'])
dataframe = pd.DataFrame(customer_info,columns = ['First','Last','Zip','Phone'])
dataframe["validZip"] = dataframe.Zip.str.extract(r'^([0-9]{5}(?:-[0-9]{4})?)$').fillna('')

Your version also works

import pandas as pd
customer_info = (['John', 'Summers', '22960', '434-305-6600'], 
            ['Josh', 'Williams', '40143', '270-555-1544'],
            ['Jim', 'Roberson', '21801','555-555-5555'],
            ['John', 'Adams', '223211143', '4444444444'])
dataframe = pd.DataFrame(customer_info,columns = ['First','Last','Zip','Phone'])


def zip_code(zip):
    if re.match('^[0-9]{5}(?:-[0-9]{4})?$',zip):
        return zip
    else:
        return ''

dataframe.Zip = dataframe.Zip.apply(zip_code)