如何讀取csv文件，並根據csv中的數據添加標題和新列並輸出新的csv

Question

在運行比較兩個csv文件的python腳本之后，我留下了一個新的csv文件，該文件僅列出新學生的電子郵件地址。 （稍后將使用此功能在我們的電子郵件系統中自動創建新用戶）。

但是，我需要獲取僅包含電子郵件地址的csv文件，並根據電子郵件地址中的信息，創建一個新的csv文件，其中包含firstname，lastname，email的標題，然后為每行提供相應的數據。

例：

原始csv（newemails.csv）

john.doe@mydomain.com
terry.jackson@mydomain.com
silly.sally@mydomain.com

新的CSV文件應如下所示：

firstname, lastname, email
John, Doe, john.doe@mydomain.com
Terry, Jackson, terry.jackson@mydomain.com
Silly, Sally, silly.sally@mydomain.com

這是我當前的代碼，它給了我newemails.csv文件

import csv
import os
import subprocess

def newemails():

for line in fileinput.input(r'C:\gamwork\currentstudents.csv', inplace=1):
    print(line.lower(), end='')


with open(r'C:\gamwork\previoususers.csv', 'r') as t1, 
open(r'C:\gamwork\currentstudents.csv', 'r') as t2:
    fileone = t1.readlines()
    filetwo = t2.readlines()

with open(r'C:\gamwork\newemails.csv', 'w') as outFile:
    for line in filetwo:
        if line not in fileone:
            outFile.write(line)

我真的不確定該怎么做，任何建議都非常感謝！

Answer 1

你可以嘗試這個：如果你的文件包含

john.doe@mydomain.com
terry.jackson@mydomain.com
silly.sally@mydomain.com

然后你可以做以下事情：

with open('mydata.csv', 'r') as f, open('out.csv', 'w') as out_file:
    out_file.write('First name, last name, email\n')
    for line in f:
        names, email = line.split('@')[0], line
        first, last = names.split('.')
        new_line = f'{first}, {last}, {email}'
        out_file.write(new_line)


with open('out.csv', 'r') as out_file:
    print(out_file.read())

輸出：

First name, last name, email
john, doe, john.doe@mydomain.com
terry, jackson, terry.jackson@mydomain.com
silly, sally, silly.sally@mydomain.com

Answer 2

這可以通過pandas輕松實現，請在下面找到一個示例。

import pandas as pd

df = pd.read_csv('test3.csv',  header=None, names=['Email'])
df['FirstName'] = [x.split('.')[0].title() for x in df['Email']]
df['LastName'] = [x.split('.')[1].split('@')[0].title() for x in df['Email']]
df = df.drop('Email', 1)
print(df)
df.to_csv('students.csv')

或另一種解決方案

import pandas as pd

def createFirstLastNames(row):
    firstLast = row['Email'].split('@')[0]
    firstName = firstLast.split('.')[0].title()
    lastName = firstLast.split('.')[1].title()
    return pd.Series({
        'FirstName' : firstName,
        'LastName' : lastName
    })

df = pd.read_csv('test3.csv',  header=None, names=['Email'])
df1 = df.merge(df.apply(lambda row: createFirstLastNames(row), axis=1), left_index=True, right_index=True)
df1 = df1.drop('Email', 1)
print(df1)
df1.to_csv('students.csv')

輸出如下

FirstName LastName
John      Doe
Terry  Jackson
Silly    Sally