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Re: What is the fastest way to threshold data?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg85947] Re: What is the fastest way to threshold data?
  • From: Raj <rajanikanth at gmail.com>
  • Date: Thu, 28 Feb 2008 02:54:14 -0500 (EST)
  • References: <fq3af1$fot$1@smc.vnet.net>

On Feb 27, 2:28=A0am, "Kevin J. McCann" <Kevin.McC... at umbc.edu> wrote:
> I have some 3d data {{x1,y1,z1},{x2,y2,z2},...} and I would like to set
> the z-values to zero if they fall below zero. More generally, I would
> like to set z to a threshold value if it is at or below a threshold.
> This seems as though it should be an easy enough thing to do, but the
> only way I have figured out is to parse out the z-vector, do
>
> mask=((#<thresh&) /@ zdata)/.True->0/.False->1;
>
> then
> zvector = zvector*mask;
>
> and rebuild the {x,y,z} data.
>
> Kevin
> --
>
> Kevin J. McCann
> Research Associate Professor
> JCET/Physics
> Physics Building
> University of Maryland, Baltimore County
> 1000 Hilltop Circle
> Baltimore, MD 21250

You probably need Clip:

 L[[All,3]]=Clip[L[[All,3]],{0,Infinity}]


Cheers,

Raj


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