Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2000
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2000

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Need to reduce 2 lists so that only {x,y} pairs with same x remain

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24173] Re: Need to reduce 2 lists so that only {x,y} pairs with same x remain
  • From: Harald Giese <giese at ifm.uni-hamburg.de>
  • Date: Wed, 28 Jun 2000 22:50:54 -0400 (EDT)
  • Organization: Institut fuer Meereskunde, Universitaet Hamburg
  • References: <8jc73k$dg3@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

materialsscientist at my-deja.com wrote:
> 
> Hello,
> 
> I have 2 lists of data:
> 
> for example
> data1={{1,1},{1.5,1.5},{2,2},{3,3},{4,4},{5,5}}
> 
> data2={{1,2},{2,3},{3,4},{4,5},{6,7},{7,8}}
> 
> I want to do a point by point comparision, so I
> need to reduce both data1 and data2 so that
> common x data in the {x,y} pairs for each list
> remain.
> 
> Thus the lists should look like this:
> 
> data1={{1,1},{2,2},{3,3},{4,4}}
> data2={{1,2},{2,3},{3,4},{4,5}}
> 
> What function(s) would to something like this?
> 


Hi Chuck,

Try this:

pos1in2 = Position[First /@ data1, #] & /@ (First /@ data2) // Flatten
newdata1 = data1[[pos1in2]]

pos2in1 = Position[First /@ data2, #] & /@ (First /@ data1) // Flatten
newdata2 = data2[[pos2in1]]

Regards,
Harald

-- 

Harald Giese
Email: giese at dkrz.de
Phone: +49 (0)40 42838 5796; Fax: +49 (0)40 5605724
Institut fuer Meereskunde der Universitaet Hamburg
(Institute of Oceanography of the University of Hamburg)
Troplowitzstrasse 7, D-22529 Hamburg


  • Prev by Date: Re: Integration...
  • Next by Date: Re: AIX 4.3 Mathematica MathKernel Out of Memory
  • Previous by thread: Re: Need to reduce 2 lists so that only {x,y} pairs with same x remain
  • Next by thread: RE: Need to reduce 2 lists so that only {x,y} pairs with same x remain