Services & Resources / Wolfram Forums / MathGroup Archive

MathGroup Archive 2008

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

Search the Archive

What is the fastest way to threshold data?

  • To: mathgroup at
  • Subject: [mg85898] What is the fastest way to threshold data?
  • From: "Kevin J. McCann" <Kevin.McCann at>
  • Date: Wed, 27 Feb 2008 04:24:39 -0500 (EST)
  • Organization: University System of Maryland

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;

zvector = zvector*mask;

and rebuild the {x,y,z} data.


Kevin J. McCann
Research Associate Professor
Physics Building
University of Maryland, Baltimore County
1000 Hilltop Circle
Baltimore, MD 21250

  • Prev by Date: Re: Matrix Differentiation
  • Next by Date: Re: Plotting Time Series
  • Previous by thread: Re: Export Data from Mathematica to Excel
  • Next by thread: Re: What is the fastest way to threshold data?