在python中如何比较两个列表，我们可以不区分大小写吗？

Question

如果当前_用户中存在“Maurya”，则不应接受“Maurya”作为可用用户名

current_users = ["amit", "ajit", "nishant", "mohit", "Maurya"]
new_users = ["deepak", "manish", "maurya", "akhil", "ajit"]

for new_user in new_users:
    if new_user in current_users:
        print(f"{new_user}, you need to enter new username!")
    else:
        print(f"{new_user}, This username is available.")

Answer 1

for new_user in new_users:
    for current_user in current_users:
        if new_user.lower() == current_user.lower():
            print('new user {} allready present'.format(new_user))

Answer 2

在我看来，一种更可靠的方法是使用case-folding，因为它对于比较不一定是平面印度名称的名称非常有用。此外，在性能方面，它恰好提供了比str.lower（）更多的*方法

代码：

current_users = ["amit", "ajit", "nishant", "mohit", "Maurya"]
new_users = ["deepak", "manish", "maurya", "akhil", "ajit"]

for new_user in new_users:
  if new_user in map(str.casefold, current_users):
    print(f"{new_user}, you need to enter new username!")
  else:
    print(f"{new_user}, This username is available.")

输出：

>>> deepak, This username is available.
>>> manish, This username is available.
>>> maurya, you need to enter new username!
>>> akhil, This username is available.
>>> ajit, you need to enter new username!

但是所有其他的方法都很有效

Answer 3

如果你关心性能，并且你的投入很大，那么在回答solid.py给出的问题的基础上做几件事

1. 将当前用户转换为集合
2. 使用循环中的设置

current_users = ["amit", "ajit", "nishant", "mohit", "Maurya"]
current_user_set = {user.lower() for user in current_users}

new_users = ["deepak", "manish", "maurya", "akhil", "ajit"]

for new_user in [user.lower() for user in new_users]:
    if new_user in current_user_set:
        print(f"{new_user}, you need to enter new username!")
    else:
        print(f"{new_user}, This username is available.")