[R] help with simple function

T.D.Rudolph prairie.picker at gmail.com
Tue May 27 21:42:40 CEST 2008



I have a matrix of frequency counts from 0-160.
x<-as.matrix(c(0,1,0,0,1,0,0,0,1,0,0,0,0,1))

I would like to apply a function creating a new column (x[,2])containing
values equal to:
a) log(x[m,1]) if x[m,1] > 0; and
b) for all x[m,1]= 0, log(next x[m,1] > 0 / count of preceding zero values
+1)

for example, x[1,2] should equal log(x[2,1]/2) = log(1/2) = -0.6931472
whereas x[3,2] should equal log(x[5,1]/3) = log (1/3) = -1.098612

I will be applying this to nrow(x)=~70,000 so I would prefer to not do it by
hand!
Tyler



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