On 21/04/2008, at 10:05 PM, William Simpson wrote: > Hi everyone, > > I would like to do the following. > > Given matrix m and matrix n, I would like to compute mn[i,,j]= m[i,,j] > + n[i,,j] if either of these elements is 0. (In other words, whichever > number is nonzero.) > Else I want mn[i,,j]=(m[i,,j] + n[i,,j])/2 > I need a fast method.
I don't know what you're doing with those double commas --- if m and n are indeed matrices they make no sense --- but if they should actually be just commas then what you want is mn <- ifelse(m==0 | n==0,m+n,(m+n)/2) cheers, Rolf Turner ###################################################################### Attention:\ This e-mail message is privileged and confid...{{dropped:9}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.