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MathGroup Archive 2002

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Re: List processing

  • To: mathgroup at smc.vnet.net
  • Subject: [mg37249] Re: List processing
  • From: "Carl K. Woll" <carlw at u.washington.edu>
  • Date: Fri, 18 Oct 2002 05:17:36 -0400 (EDT)
  • Organization: University of Washington
  • References: <aokbp7$afv$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi John,

I remember there being a similar thread on this subject a while ago, but I
am too lazy to check it out. The simplest solution seems to be using
Interval, although it may not be very fast. For example

In[3]:=
Interval[{100,200},{150,250},{120,270},{300,400}]
Out[3]=
Interval[{100, 270}, {300, 400}]

If the above is not sufficiently fast for you, then you may want to search
the archives for the thread I mentioned above.

Carl Woll
Physics Dept
U of Washington

"John Leary" <leary at paradise.net.nz> wrote in message
news:aokbp7$afv$1 at smc.vnet.net...
> 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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