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Re: List processing

  • To: mathgroup at
  • Subject: [mg37251] Re: List processing
  • From: Mark Westwood <MarkCWestwood at>
  • Date: Fri, 18 Oct 2002 05:17:51 -0400 (EDT)
  • References: <aokbp7$afv$>
  • Sender: owner-wri-mathgroup at


The simplest solution to your trial problem that I could come up with
was the following:

Apply[List, Apply[Interval, {{100, 200}, {150, 250}, {120, 270}, {300,

I hope you can figure it out.  I didn't test it on a larger input
dataset - my usual experience is that built-in functions are faster for
operations on lists than fiddling around with loops.

Mark Westwood

John Leary wrote:
> Greetings
> This problem can be solved by conventional programming, but I wonder if
> there is an elegant Mathematica solution ?
> A list contains pairs of values, with each pair representing the lower and
> upper edge of a sub-range.  Some of the sub-ranges partially overlap, some
> fully overlap, others don't overlap at all.  The problem is to produce a
> second list that contains the overall upper and lower edges of the
> overlapping sub-ranges.
> A simple example :  {{100,200},{150,250},{120,270},{300,400}}  would result
> in {{100,270},{300,400}}.
> In the real case, the input list has several hundred elements and the
> output list typically has five elements.
> I have a working solution based on loops, but there must be a more elegant
> one.  I would be very grateful for any suggestions.
> Best regards
> John Leary

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