I humbly seek the wisdom of the Monks.

Given a list of Set::IntSpan objects I'd like to find the number of overlapping ranges for any given value. For example, given the three ranges represented here:

  --XXXXXXXXX---  a = 3-11
  ----XXXX------  b = 5-8
  ------XXXXX---  c = 7-11

I'd like to end up with these values: 

  00112233222000

For my use-case I know that each span is just one contiguous range - there are no holes in the spans. Also, the spans may be large so iterating over the elements of a span isn't an option.

I think the first step would be to split ranges which overlap other ranges into separate non-overlapping ranges: 

  --XX---------- a1 = 3-4
  ----XXXX------ a2 = 5-8
  --------XXX--- a3 = 9-11
  ----XXXX------ b  = 5-8
  ------XX------ c1 = 7-8
  --------XXX--- c2 = 9-11

then a simple $hash{ $stringified_span }++ would give me the counts.

Any suggestions for how to do this efficiently? Or a different approach? (I've thousands of spans representing events with durations from a log)

In reply to Efficient algorithm needed to split Set::IntSpan objects by tim.bunce

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