Re: Setting Negatives to Zero

*To*: mathgroup at smc.vnet.net*Subject*: [mg82822] Re: [mg82736] Setting Negatives to Zero*From*: Carl Woll <carlw at wolfram.com>*Date*: Wed, 31 Oct 2007 06:25:03 -0500 (EST)*References*: <200710300826.DAA13428@smc.vnet.net>

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 > > I think the fastest approach will be to use the function Clip: Clip[data, {0, Infinity}] By the way, I discussed some methods for efficiently programming tasks like yours in Mathematica in my talk at the 2007 Wolfram Technology Conference, which you can find at: http://library.wolfram.com/infocenter/Conferences/7005/ Carl Woll Wolfram Research

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