Re: Setting Negatives to Zero

*To*: mathgroup at smc.vnet.net*Subject*: [mg82794] Re: [mg82736] Setting Negatives to Zero*From*: János <janos.lobb at yale.edu>*Date*: Wed, 31 Oct 2007 06:10:39 -0500 (EST)*References*: <200710300826.DAA13428@smc.vnet.net>

On Oct 30, 2007, at 4:26 AM, Kevin J. McCann wrote: > I have a very large data set (64000 x 583) in which negative values > indicate "no data", unfortunately these negatives are not all the > same. > I would like to efficiently set all these negatives to zero. I know = > that > I will likely be embarrassed when I see how to do it, but I can't seem > to remember or figure it out. I should emphasize that because of the > size of the data set, this needs to be done efficiently. Another > programming language does it as follows: > > x(x < 0) = 0; > > Thanks, > > Kevin > -- > > Kevin J. McCann > Research Associate Professor > JCET/Physics > Physics Building > University of Maryland, Baltimore County > 1000 Hilltop Circle > Baltimore, MD 21250 if your data set is called lst, then my newbie approach would be: In[7]:= Map[If[#1 < 0, 0, #1] & , lst, {2}] J=E1nos ------------------------------------------------- clear perl code is better than unclear awk code; but NOTHING comes close to unclear perl code http://www.faqs.org/faqs/computer-lang/awk/faq/

**References**:**Setting Negatives to Zero***From:*"Kevin J. McCann" <Kevin.McCann@umbc.edu>