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