Split a character string based on change of character

Split a character string based on change of character is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

Split a (character) string into comma (plus a blank) delimited strings based on a change of character   (left to right).

Show the output here   (use the 1^st example below).

Blanks should be treated as any other character   (except they are problematic to display clearly).   The same applies to commas.

For instance, the string:

 gHHH5YY++///\ 

should be split and show:

 g, HHH, 5, YY, ++, ///, \ 

Haskell

<lang Haskell>import Data.List (group, intercalate)

main :: IO () main = putStrLn $ intercalate ", " (group "gHHH5YY++///\\")</lang>

Output:

g, HHH, 5, YY, ++, ///, \

Python

<lang python>import itertools

try: input = raw_input except: pass

s = input() groups = [] for _, g in itertools.groupby(s):

   groups.append(.join(g))

print(' input string: %s' % s) print(' output string: %s' % ', '.join(groups))</lang>

Output:

  when using the default input

      input string:  gHHH5YY++///\
     output string:  g, HHH, 5, YY, ++, ///, \

REXX

<lang rexx>/*REXX program splits a string based on change of character ───► a comma delimited list.*/ parse arg str . /*obtain optional arguments from the CL*/ if str== | str=="," then str= 'gHHH5YY++///\' /*Not specified? Then use the default.*/ p=left(str, 1) /*placeholder for the "previous" string*/ $= /* " " " output " */

     do j=1  for length(str);      @=substr(str, j, 1)    /*obtain a char from string. */
     if @\==left(p, 1)   then do;  $=$',' @;  p=;  end    /*different then previous?   */
                         else      $=$ || @               /*a replicated character.    */
     p=p || @                                             /*append char to current list*/
     end   /*j*/

say ' input string: ' str say ' output string: ' $ /*stick a fork in it, we're all done. */</lang> output   when using the default input:

      input string:  gHHH5YY++///\
     output string:  g, HHH, 5, YY, ++, ///, \