Re: List processing

• To: mathgroup at smc.vnet.net
• Subject: [mg37251] Re: List processing
• From: Mark Westwood <MarkCWestwood at compuserve.com>
• Date: Fri, 18 Oct 2002 05:17:51 -0400 (EDT)
• References: <aokbp7\$afv\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```John

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,
400}}]]

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.

Regards
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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