[R] Faster process for creating a matrix based on matrix element comparison

Evgenia evgts at aueb.gr
Fri Oct 28 20:40:12 CEST 2011


I have matrix data
data<-matrix(cbind(c(0,0,0),c(NA,0,1),c(1,1,1),c(0,1,1)),ncol=3)
and I want to create a new matrix by checking each element of the data and
put value 0 if i have NA and 1 otherwise.
For this reason i made the function below 
pdata<-matrix(NA,ncol=ncol(data),nrow=nrow(data))

pdata<-sapply(1:nrow(data),function(i) sapply (1:ncol(data),function(j)
if (is.na(data[i,j])) {pdata[i,j]<-0} else {pdata[i,j]<-1}
))
pdata<-matrix(t(pdata),ncol=ncol(data),nrow=nrow(data))

with pdata 

> pdata
     [,1] [,2] [,3]
[1,]    1    1    1
[2,]    1    1    1
[3,]    1    1    1
[4,]    0    1    1

But in my case I have a matrix with 50000 rows and 10 colums
and the creation of pdata takes alot of time.
Could anyone have any suggestion to make pdata faster?
Thanks




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