Given a sequence of letters, output only the vowels.

Input

• A sequence of letters
• This may be a string or any ordered data structure of characters (provided it is consistent between inputs)
• The letters may contain a mixture of upper and lower case
• The characters that count as letters for this challenge are A-Z and a-z, specifically ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
• The input may be empty (it may have length zero)

Output

• All of the vowels from the input, in the same order, and nothing else
• This may be a string or any ordered data structure of characters. It does not need to match the input format (provided it is consistent between inputs)
  • For example, you may take input as an array of characters, and output as a string, provided this does not change for different inputs
• Vowels that appear more than once in the input must appear the same number of times in the output
• If there are no vowels in the input, the output is empty (a sequence of length zero)
• The characters that count as vowels for this challenge are AEIOUaeiou
• Case must be maintained - a vowel that is lower case in the input must be lower case in the output, and a vowel that is upper case in the input must be upper case in the output

Test cases

Test cases are in the format "input" : "output"

"" : ""
"q" : ""
"S" : ""
"Rhythm" : ""
"a" : "a"
"art" : "a"
"atr" : "a"
"rat" : "a"
"rta" : "a"
"tar" : "a"
"tra" : "a"
"emu" : "eu"
"eum" : "eu"
"meu" : "eu"
"mue" : "ue"
"uem" : "ue"
"ume" : "ue"
"AaeEIiOouU" : "AaeEIiOouU"
"aaaaaaaa" : "aaaaaaaa"
"bbbbbbbb" : ""
"abababab" : "aaaa"
"babababa" : "aaaa"
"aLtErNaTe" : "aEae"

Explanations are optional, but I'm more likely to upvote answers that have one.

posted about 2 years ago

CC BY-SA 4.0

2y ago

trichoplax‭

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