[英]How to change a .csv into lists and vice versa in python?
我需要分割一個.csv文件:
user1,pass1,email1
user2,pass2,email2
user3,pass3,email3
分為3個可以單獨調用和附加的列表。
with open('userdata.csv', 'r') as f:
userlist = [row[0] for row in csv.reader(f)]
passlist = [row[1] for row in csv.reader(f)]
emaillist = [row[2] for row in csv.reader(f)]
print(userlist)
print(passlist)
print(emaillist)
我需要以下代碼來返回:
['user1', 'user2', 'user3']
['pass1', 'pass2', 'pass3']
['email1, 'email2', 'email3']
但這就是我得到的:
['user1', 'user2', 'user3']
[]
[]
一旦成功,我還需要一種將其寫為.csv的方式,該格式將與我調用它時的格式完全相同,但帶有附加信息,因此可以在需要時再次調用它。
您正在嘗試通過重復調用csv.reader(f)
來使用三次csv文件。
您可以將行存儲在臨時列表中,並從該列表中獲取列。
with open('userdata.csv', 'r') as f:
rows = list(csv.reader(f))
userlist = [row[0] for row in rows]
passlist = [row[1] for row in rows]
emaillist = [row[2] for row in rows]
從行中選擇列的一種更優雅的方法是使用zip
:
with open('userdata.csv', 'r') as f:
userlist, passlist, emaillist = zip(*(row for row in csv.reader(f)))
為了編寫csv文件,可以將zip
用於另一個方向,以將列轉換回行:
with open('output.csv', 'w', newline='') as f:
csv.writer(f).writerows(zip(userlist, passlist, emaillist))
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