count consecutive elements

[Tim Chase]

On 2021-01-13 21:20, Bischoop wrote:
> I want to  to display a number or an alphabet which appears mostly
> consecutive in a given string or numbers or both
> Examples
> s= ' aabskaaabadcccc'
> output: c
> # c appears 4 consecutive times
>  8bbakebaoa
> output: b
> #b appears 2 consecutive times

I'd break the problem into two parts:

1) iterate over your thing (in this case, a string) and emit the item
and its correpsonding count of consecutive matches.

2) feed that into something that finds the longest run(s) output by
that.

So off the cuff, something like

  def consecutive_counter(seq):
      # I'm not sure if there's something
      # like this already in itertools
      cur = nada = object()
      count = 0
      for x in seq:
          if x == cur:
              count += 1
          else:
              if cur is not nada:
                  yield cur, count
              cur = x
              count = 1
      if cur is not nada:
          yield cur, count

  def longest(seq):
      results = []
      biggest = 0
      for item, count in seq:
          if count > biggest:
              results = [item]
              biggest = count
          elif count == biggest:
              results.append(item)
      return results, biggest

  for s in (
          "",
          "a",
          "aaa",
          "aaabbb",
          "aabskaaabadcccc",
          "aabskaaakkkkkbadcccc",
          ):
      print("Testing %r" % s)
      print(repr(longest(consecutive_counter(s))))

-tkc