Python: print input in reverse order (conditions: only words (at least 4 words))

Question

I need to print input from the user in reverse order using a function. As a condition, just words (no floats/ int) should be allowed & at least four words need to be entered. e.g.: How can I help you --> you help I can How

It should'nt be possible to input: "4 5 6 7" or "There are 2 dogs" Here's my current code, however I didn't integrate that only strings are allowed so far:

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()

I tried with if n<4 and words == str:, if n<4 and words != string etc.. However, that didn't work. Could you please help me solving this issue? Maybe my code is wrong in general.

Please include the code in the body of your post, not an image.. — Justin, Mar 24 '21 at 13:01
You'll have to check each word. [Checking if a string can be converted to float in Python](https://stackoverflow.com/a/736050) — 001, Mar 24 '21 at 13:08
When asking on S/O It is *really very helpful* to show an example of what is input and how you want it output, especially if your code isn't working. It's also very helpful as an exercise when coding. — Konchog, Mar 24 '21 at 13:12

Konchog · Accepted Answer · 2021-03-24T13:41:24.610

0

Reduce the problem to it's essential elements. The following should work - but your question looks suspiciously like homework.

    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.

result:

example an for this test

If you need to filter numerics..

    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.

result:

example an for this test

If you need to reject numerics / responses with less than 4 words in a function.

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

edited Mar 24 '21 at 13:41

answered Mar 24 '21 at 13:04

Konchog

1,920
19
23

I had a similar solution first. But I need to use "functions" and want to limit the input to "strings" (no numbers). How can I do that? – Näs Mar 24 '21 at 13:13
@Näs, I don't understand - do you want numbers rejected? As I say under your question, you need to show some example of what you want to happen. – Konchog Mar 24 '21 at 13:15
Yes numbers should be rejected. Example Input: How can i help you --> print: you help i can How. If the user enters numbers i want to ask the him for new input and not to include numbers – Näs Mar 24 '21 at 13:28
If you like it, then mark it as useful as well as being an answer! – Konchog Mar 24 '21 at 13:44

score 0 · Answer 2 · answered Mar 24 '21 at 13:13

0

It is a little bit nasty, but might be useful for you to check for nums! :)

inp = input()

try:
    int(inp)
except ValueError:
    # do your operations here

answered Mar 24 '21 at 13:13

Deniz Polat

26
3

Python: print input in reverse order (conditions: only words (at least 4 words))

2 Answers2