python如何将字段进行拆分

import pandas as pd

data = pd.DataFrame({ 'Country':['China','American','Japan'],
                      'City': ['shanghai|Shenzhen|beijing','New York|shanghai|Shenzhen|beijing | Texas','Tokyo|Osaka'],
                      'GDP': ['88,89,43','123,45,46,99,123','123,63,24']
              })
data

def col_to_row(data,col,delim):
    '''
    '''
    col_split = data[col].str.split('%s'%(delim))  # '%s'%(',')
    max_length = max(col_split.apply(lambda x: len(x)))
    split_name = ['%s%s'%(col,i) for i in range(1,max_length+1)]
    col_split_df =  data[col].str.split('%s'%(delim),expand=True)
    col_split_df.columns   = split_name
    data_split = data.join(col_split_df)

    return data_split

col_to_row(data,'GDP',',')

col_to_row(data,'City','|')

data

col_to_row(data,‘GDP’,‘,’)

col_to_row(data,‘City’,‘|’)