How to rotate letters in a python string-CodePudding

Create a scrolling_text function that accepts a string as a parameter, sequentially rearranges all the characters in the string from the zero index to the last one, and returns a list with all the received combinations in upper case.

def scrolling_text(string: str) -> list:
    pass

Example`

scrolling_text("robot")

returns:
[ "ROBOT",
  "OBOTR",
  "BOTRO",
  "OTROB",
  "TROBO" ]

I know only I return the list in uppercase

CodePudding user response：

The easiest way is to use slices of the string, which is an easy way of getting a subset of an sequence. In Python, str can be treated as a sequence of characters.

The following function would do it:

def scrolling_text(text: str) -> list[str]:
    ret = []
    for i in range(len(text)):
        ret.append(text[i:]   text[:i])
    return ret

So this goes through every offset starting at zero and going up to the number of characters in the string. The expression text[i:] represents the substring from offset i onwards, and text[:i] represents the substring up to (but not including) I.

If you wanted more advanced Python, you could use a list comprehension:

def scrolling_text(text: str) -> list[str]:
    return [text[i:]   text[:i] for i in range(len(text))]

Or you could use a generator to lazily evaluate the list:

from typing import Iterator

def scrolling_text(text: str) -> Iterator[str]:
    for i in range(len(text)):
        yield text[i:]   text[:i]

CodePudding user response：

This is a pretty basic python code:

def scrolling_text(string: str) -> list:
    out = []
    string = string.upper()
    for i in range(len(string)):
        out.append(string[i:]   string[:i])
    return out
        
res = scrolling_text("ROBOT")
print(res)  # ['ROBOT', 'OBOTR', 'BOTRO', 'OTROB', 'TROBO']