Ruby: How to sort a string while keeping some characters in place?

Question

I am new to Ruby and I would like to sort the string, but keeping non-literal characters in place. For instance:"hello, sally! seen 10/dec/2016" => "ehllo, allsy! eens 01/cde/0126"

I tried:

word.scan(/\w+/).collect { |e| ((e.scan /\w/).sort.join)}
#=> ["ehllo", "allsy", "eens", "01", "cde", "0126"]

But I can’t understand how to return non-alphanumeric characters.

Answer 1

But I can’t understand how to return non-alphanumeric characters.

It would be easier not to delete them first:

str = "hello, sally! seen 10/dec/2016"

str.gsub(/\w+/) { |m| m.chars.sort.join }
#=> "ehllo, allsy! eens 01/cde/0126"

gsubIt scans a line for the template matching, and transmits each block row, so called unit via "hello", "sally", "seen", "10", "dec"and "2016". It sorts the string with:

m = "hello"
m.chars #=> ["h", "e", "l", "l", "o"]
 .sort  #=> ["e", "h", "l", "l", "o"]
 .join  #=> "ehllo"

gsub then replaces the result of the block to match.

Answer 2

: "... , ". , , , . , .

def sort_alphas(str)
  alphas, non_alphas = str.each_char.with_index.partition { |c,_| c =~ /[[:alpha:]]/ }
  chrs, offsets = alphas.transpose
  chrs.sort.zip(offsets).concat(non_alphas).sort_by(&:last).map(&:first).join
end

str = "hello, sally! seen 10/dec/2016"
sort_alphas(str)
  #=> "acdee, eehll! llno 10/ssy/2016"

.

alphas, non_alphas = str.each_char.with_index.partition { |c,_|
  c =~ /[[:alpha:]]/ }
alphas
  #=> [["h", 0], ["e", 1], ["l", 2], ["l", 3], ["o", 4], ["s", 7], ["a", 8],
  #    ["l", 9], ["l", 10], ["y", 11], ["s", 14], ["e", 15], ["e", 16],
  #    ["n", 17], ["d", 22], ["e", 23], ["c", 24]]
non_alphas
  #=> [[",", 5], [" ", 6], ["!", 12], [" ", 13], [" ", 18], ["1", 19], ["0", 20],
  #    ["/", 21], ["/", 25], ["2", 26], ["0", 27], ["1", 28], ["6", 29]] 
chrs, offsets = alphas.transpose
chrs
  #=> ["h", "e", "l", "l", "o", "s", "a", "l", "l", "y", "s", "e", "e", "n",
  #    "d", "e", "c"] 
offsets
  #=> [0, 1, 2, 3, 4, 7, 8, 9, 10, 11, 14, 15, 16, 17, 22, 23, 24]

sorted_alphas = chrs.sort.zip(offsets)
  # => [["a", 0], ["c", 1], ["d", 2], ["e", 3], ["e", 4], ["e", 7], ["e", 8],
  #     ["h", 9], ["l", 10], ["l", 11], ["l", 14], ["l", 15], ["n", 16],
  #     ["o", 17], ["s", 22], ["s", 23], ["y", 24]] 
sorted_arr = sorted_alphas.concat(non_alphas)
  #=> [["a", 0], ["c", 1], ["d", 2], ["e", 3], ["e", 4], ["e", 7], ["e", 8],
  #    ["h", 9], ["l", 10], ["l", 11], ["l", 14], ["l", 15], ["n", 16], ["o", 17],
  #    ["s", 22], ["s", 23], ["y", 24], [",", 5], [" ", 6], ["!", 12], [" ", 13], 
  #    [" ", 18], ["1", 19], ["0", 20], ["/", 21], ["/", 25], ["2", 26], ["0", 27],
  #    ["1", 28], ["6", 29]] 
ordered_arr = sorted_arr.sort_by(&:last)
  #=> [["a", 0], ["c", 1], ["d", 2], ["e", 3], ["e", 4], [",", 5], [" ", 6],
  #    ["e", 7], ["e", 8], ["h", 9], ["l", 10], ["l", 11], ["!", 12], [" ", 13],
  #    ["l", 14], ["l", 15], ["n", 16], ["o", 17], [" ", 18], ["1", 19], ["0", 20],
  #    ["/", 21], ["s", 22], ["s", 23], ["y", 24], ["/", 25], ["2", 26], ["0", 27],
  #    ["1", 28], ["6", 29]] 
ordered_chrs = ordered_arr.map(&:first)
  #=> ["a", "c", "d", "e", "e", ",", " ", "e", "e", "h", "l", "l", "!", " ", "l",
  #    "l", "n", "o", " ", "1", "0", "/", "s", "s", "y", "/", "2", "0", "1", "6"] 
ordered_chrs.join
  #=> "acdee, eehll! llno 10/ssy/2016"