Python：在循环中将值写入csv

Question

我尝试在循环中写入一些值，但我的csv文件为空。

我有df

domain  surname name    patronymic
erlyvideo.ru    Лапшина Юлия    Юрьевна
finteca.ru  Крылов  Александр   Александрович

我用

with open('emails.csv','w') as f1:
writer = csv.writer(f1)
for i, (sur, name, patr, dom) in enumerate(zip(df.surname.values.tolist(), df.name.values.tolist(), df.patronymic.values.tolist(), df.domain.values.tolist())):
    sur = translit(sur, "ru", reversed=True).replace("'", '')
    name = translit(name, "ru", reversed=True).replace("'", '')
    patr = translit(patr, "ru", reversed=True).replace("'", '')
    all_email = []
    var0 = 'edevyataykina' + '@' + str(dom)
    var1 = str(sur) + '@' + str(dom)
    var2 = str(name) + '@' + str(dom)

    all_email.extend([var1, var2])
    if validate_email(var0, check_mx=True) == True and validate_email(var0, verify=True) == True:
        res_mail = 'Catch_All'
    elif validate_email(var0, check_mx=True) == False:
        res_mail = 'DomainName Not Found'
    elif validate_email(var0, check_mx=True) == True and validate_email(var0, verify=True) == None:
        valid_email = []
        for mail in all_email:
            is_valid = validate_email(mail, verify=True)
            time.sleep(1)
            if is_valid is True:
                valid_email.append(mail)
        if len(valid_email) == 1:
            res_mail = valid_email[0]
        else:
            res_mail = 'Username Not Found'
            print res_mail
    writer.writerow(res_mail)

为什么我可以在循环或text_file中将所有值res_mail写入csv？