Re: What is the fastest way to threshold data?

*To*: mathgroup at smc.vnet.net*Subject*: [mg85959] Re: [mg85898] What is the fastest way to threshold data?*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 28 Feb 2008 03:00:27 -0500 (EST)*Reply-to*: hanlonr at cox.net

data /. {x_, y_, z_?Negative} -> {x, y, 0} or more generally for a threshold data /. {x_, y_, z_ /; z < threshold} -> {x, y, threshold} Bob Hanlon ---- "Kevin J. McCann" <Kevin.McCann 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 >