Python：按相反顺序打印输入（条件：仅字（至少4字））

Question

我需要使用函数以相反的顺序打印用户的输入。作为一个条件，只允许字（无浮点数/int）；至少需要输入四个单词。 例如。： 我能为您效劳吗 --&燃气轮机；你能帮我吗

不能输入“4 5 6 7”或“有2条狗” 这是我当前的代码，但是我没有集成到目前为止只允许使用字符串：

def phrase():
    while True:
        user_input = input("Please insert a phrase: ")
        words = user_input.split(" ")
        n = len(words)
        if n >= 4:
            words = words[-1::-1]
            phrase_reverse = " ".join(words)
            print(phrase_reverse)
        else:
            print("Please only insert words and at least 4 ")
            continue
        break


phrase()

我试过if n<4 and words == str:、if n<4 and words != string等等。。然而，这不起作用。你能帮我解决这个问题吗？也许我的代码总的来说是错的

Answer 1

将问题归结为基本要素。 下面的问题应该是可行的，但是你的问题看起来很像家庭作业

    text = "test this for an example"  # use a text phrase to test.
    words = user_input.split().        # space is default for split.
    print(" ".join(reversed(words)))   # reverse list, and print as string.

结果:

example an for this test

如果你需要过滤数字

    text = "test this for an 600 example" # use a text phrase to test.
    words = text.split()           # space is default for split.
    print(" ".join(reversed([wd for wd in words if not wd.isnumeric()])))
# filter, reverse, and print as string.

结果:

example an for this test

如果您需要拒绝函数中少于4个单词的数字/响应

def homework(text: str) -> bool:
    words = text.split()
    composed = list(reversed([wd for wd in words if not wd.isnumeric()]))
    result = len(words) == len(composed) and len(words) > 3
    if result:
        print(' '.join(composed))
    return result