我在csv文件中有数据，如下所示：
fromaddress, toaddress, timestamp
sender1@email.com, recipient1@email.com, recipient2@email.com, 8-1-2015
sender2@email.com, recipient1@email.com, 8-2-2015
sender3@email.com, recipient1@email.com, recipient2@email.com, recipient3@email.com, recipient4@email.com, 8-3-2015
sender1@email.com, recipient1@email.com, recipient2@email.com, recipient3@email.com, 8-4-2015
使用Python，我想生成一个类似于：
的txt文件sender1_email.com, recipient1_email.com
sender1_email.com, recipient2_email.com
sender2_email.com, recipient1_email.com
sender3_email.com, recipient1_email.com
sender3_email.com, recipient2_email.com
sender3_email.com, recipient3_email.com
sender3_email.com, recipient4_email.com
sender1_email.com, recipient1_email.com
sender1_email.com, recipient2_email.com
sender1_email.com, recipient3_email.com
最终，我想这整个过程将需要几个步骤。在读取csv文件后，我将需要为fromaddress和toaddress创建单独的列表（我完全忽略了timestamp列）。 fromaddress列中每行只有一个电子邮件地址，但是toaddress列中每行有多个电子邮件地址。我需要为每行列出的每个toaddress电子邮件地址复制fromaddress电子邮件地址。完成后，我需要用下划线（_）符号替换所有@符号。最后，当我写txt文件时，我需要在每一行之间添加一个额外的空格，以便它是“双倍行距”
我还没有走得太远，因为我是一名Python新手，而且我已经陷入了第一步。以下代码复制了toaddress列中每个字符的fromaddress，而不是每个单独的电子邮件地址。我也需要有关toaddress列表的帮助。有人可以帮忙吗？
import csv
fromaddress = []
toaddress = []
with open("filename.csv", 'r') as f:
c = csv.reader(f, delimiter = ",")
for row in c:
for item in row[1]:
fromaddress.append(row[0]);
print(fromaddress)
每个人，感谢您的帮助！我尝试了所有代码，但不幸的是我没有得到我需要的输出。而不是得到这个（我想要的）：
sender1_email.com, recipient1_email.com
sender1_email.com, recipient2_email.com
sender1_email.com, recipient3_email.com
sender2_email.com, recipient1_email.com
sender3_email.com, recipient1_email.com
sender3_email.com, recipient2_email.com
我得到了这个：
sender1_email.com,"recipient1_email.com, recipient2_email.com, recipient3_email.com"
sender2_email.com,"recipient1_email.com"
sender3_email.com,"recipient1_email.com, recipient2_email.com"
每个“fromaddress”行中只有1个元素，但每个“toaddress”行中有多个元素。基本上，我必须将每个收件人地址与正确的发件人地址配对。我想我没有得到正确的输出，因为csv文件中的（“）双引号包围了每一行中的所有发件人地址。
答案 0 :(得分：0)
for row in c:
for item in row[1]:
fromaddress.append(row[0]);
for item in row[1]只会查看每行中的第二个元素。如果要遍历每一行，然后将列元素分配给变量，您需要这样：
for row in c:
fromaddress.append(row[0]);
toaddress.append(row[1]);
# etc...
答案 1 :(得分：0)
这可以解决您的问题：
f = open("file.txt", "r")
output = open("output.txt", "w")
for line in f.readlines()[1:]: # splitting file into lines, excluding the first one
fields = line.split(", ") # splitting line into separate fields
for mail in fields[1:len(fields)-1]: # iterating on recepients (excluding first and last element from "fields" list)
output.write(fields[0] + " " + mail + "\n")
f.close()
output.close()
答案 2 :(得分：0)
如果第一个电子邮件地址始终是发件人地址，并且连续的最后一项始终是无用值（日期），则可以执行以下操作。
test.txt输入文件
sender1@email.com, recipient1@email.com, recipient2@email.com, 8-1-2015
sender2@email.com, recipient1@email.com, 8-2-2015
sender3@email.com, recipient1@email.com, recipient2@email.com, recipient3@email.com, recipient4@email.com, 8-3-2015
sender1@email.com, recipient1@email.com, recipient2@email.com, recipient3@email.com, 8-4-2015
python代码
import csv
storage = [] #here we store our sender-receiver pairs
with open('test.txt','rb') as f: #open the input text file
for row in csv.reader(f, delimiter=','): #loop through every line of the input file
storage.extend([(row[0].replace('@','_'),x.replace('@','_')) for x in row[1:-1]]) #add a sender-receiver pair to the storage list
#here we loop through the storage list and write line by line to the `new.text` file.
for pair in storage:
with open("new.txt", "a") as f:
f.write(pair[0] + pair[1] + ' \n\n') #double new line!
输出new.txt
sender1_email.com recipient1_email.com
sender1_email.com recipient2_email.com
sender2_email.com recipient1_email.com
sender3_email.com recipient1_email.com
sender3_email.com recipient2_email.com
sender3_email.com recipient3_email.com
sender3_email.com recipient4_email.com
sender1_email.com recipient1_email.com
sender1_email.com recipient2_email.com
sender1_email.com recipient3_email.com
答案 3 :(得分：0)
您不需要创建单独的列表来执行您想要的操作，另外您可以使用csv模块读取输入csv文件和编写txt输出文件：
import csv
with open('mail.csv','rb') as inf, open('mail.txt', 'wb') as outf:
reader = csv.reader(inf)
next(reader) # skip header row
writer = csv.writer(outf)
for row in reader:
row = row[:-1] # remove trailing date
sender = row[0].replace('@', '_')
writer.writerows(([sender, recipient.replace('@', '_')]
for recipient in row[1:]))