[R] help:too slow

[Valery A.Khamenya]

here is a script I use to make overlapping cut of my input "col.dat"
file into a matrix:

#----------------------------------
col2mat<-function(x, sampsz=220, qsamp=2000) {
  m<-matrix(nr=qsamp, nc=sampsz)
  for(s in 1:qsamp){ 
    print(s)
    for(i in 1:sampsz){
      m[s,i] <- x[s+i,1]
    }
  }
  m
}
w<-read.table("col.dat", check.names=FALSE)
m<-col2mat(w)
#----------------------------------

the input file "col.dat" looks like this:
#-----------------------
118
118
122
.
.
.
-90
-84
-120
-108
#------------
contains about 380000 numbers and has a size of 1.5Mb. Not a small
file I understand, but not too large! However I do not use the whole
file at _this_ stage of my task, I use no more than 10% (no more than
150Kb) if it is matter. Well. 

Problem: m<-col2mat(w) works toooo slow. One row (that is 220 numbers)
of such a matrix is being formed in ~5 sec! (5*2000 = 10000 sec). it
is slowed in thousands times comparing to analogical C-code, too much
I think. 

Q1: is there a better way to create my matrix? (maybe I do some
    mistake)

Q2(for developers): if this slowdown is a problem of R's engine, may
                    we hope the problem will be corrected?

thank you.

Valery A.Khamenya (please reply-to:<news_vkhamenya at chat.ru>)


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