python csv复制列

Question

我有一个包含以下内容的文件

first_name,last_name,uid,email,dep_code,dep_name
john,smith,jsmith,[e-mail],finance,21230
john,king,jking,[e-mail],human resource,31230

我想复制“email”列并创建一个新列“email2”，然后将gmail.com从email2列替换为hotmail.com

我是python新手，所以需要专家的帮助，我尝试了一些脚本，但如果有更好的方法，请告诉我。原始文件包含60000行。

with open('c:\\Python27\\scripts\\colnewfile.csv', 'rb') as fp_in1, open('c:\\Python27\\scripts\\final.csv', 'wb') as fp_out1:
    writer1 = csv.writer(fp_out1, delimiter=",")
    reader1 = csv.reader(fp_in1, delimiter=",")
    domain = "@hotmail.com"
    for row in reader1:
        if row[2:3] == "uid":
            writer1.append("Email2")
        else:
            writer1.writerow(row+[row[2:3]])

这是最终脚本，唯一的问题是它没有完成整个输出文件，它只显示61409行，而在输入文件中有61438行。

inFile='c:\Python27\scripts\in-093013.csv'outFile='c:\Python27\scripts\final.csv'

使用open（infle，'rb'）作为fp_-in1，open（outFile，'wb'）作为fp_-out1:writer=csv.writer（fp_-out1，delimiter=“，”）reader=csv.reader（fp_-in1，delimiter=“，”）作为col-in-reader:del-col[6:]writer.writerow（col）headers=next（reader）writer）writerow（headers['email2']）作为行中的行：if-len（行）

Answer 1

这可以用熊猫非常干净地完成。在这里，它去：

In [1]: import pandas as pd

In [3]: df = pd.read_csv('your_csv_file.csv')

In [4]: def rename_email(row):
   ...:     return row.email.replace('gmail.com', 'hotmail.com')
   ...:

In [5]: df['email2'] = df.apply(rename_email, axis=1)

In [6]: """axis = 1 or ‘columns’: apply function to each row"""

In [7]: df
Out[7]:
  first_name last_name     uid             email        dep_code  dep_name              email2
0       john     smith  jsmith  [e-mail]         finance     21230  [e-mail]
1       john      king   jking   [e-mail]  human resource     31230   [e-mail]

In [8]: df.to_csv('new_update_email_file.csv')

Answer 2

如果在读卡器上调用next（），一次只能得到一行；用它来复制标题。复制电子邮件列非常简单：

import csv

infilename = r'c:\Python27\scripts\colnewfile.csv'
outfilename = r'c:\Python27\scripts\final.csv'

with open(infilename, 'rb') as fp_in, open(outfilename, 'wb') as fp_out:
    reader = csv.reader(fp_in, delimiter=",")
    headers = next(reader)  # read first row

    writer = csv.writer(fp_out, delimiter=",")
    writer.writerow(headers + ['email2'])

    for row in reader:
        if len(row) > 3:
            # make sure there are at least 4 columns
            email = row[3].split('@', 1)[0] + '@hotmail.com'
        writer.writerow(row + [email])

此代码在第一个@符号上拆分电子邮件地址，取拆分的第一部分，并在其后面添加@hotmail.com：

>>> '[e-mail]'.split('@', 1)[0]
'example'
>>> '[e-mail]'.split('@', 1)[0] + '@hotmail.com'
'[e-mail]'

以上产生：

first_name,last_name,uid,email,dep_code,dep_name,email2
john,smith,jsmith,[e-mail],finance,21230,[e-mail]
john,king,jking,[e-mail],human resource,31230,[e-mail]

对于您的示例输入。