Hello all,
I would like to read the specific line number row of a direct access file
(which is stored as a n_row*n_col matrix of elements kind=p) without reading
all the preceding lines (i.e 1,2,..,row-1).
Is there a function in R that can perform this task?
To solve my issue, I tried without to call Fortran from R by doing the
following steps:
I) I wrote a subroutine in fortran called read_binary.f90
************************************
Subroutine read_binary (n_col,row,img)
integer*1 :: im1(n_col)
integer*1 :: im2(n_col)
integer*1 :: im2(n_col)
open(10,file=binary_file,access=direct,action=read,status='old',recl=n_col*p)
if(p==1) then
read(10,rec=row) img1
img=img1
else if(p==2) then
read(10,rec=row) img2
img=img2
else
read(10,rec=row) img3
img=img3
endif
close(10)
End subroutine read_binary
************************************
II) R CMD SHLIB read_binary.f90
III) dyn.load("read_libray.so")
IV) Then in R, I tried many variant of the following function but I wasn't
able to store the line number row into the vector img
************************************
img<-c(n_col)
Read_binary<-function(n_samples,line,type) {
as.integer(n_samples),
as.intger(line),
as.integer(typ),
img=as.single(img)
}
************************************
Could anyone tell me what I'm doing wrong? I'm a beginner in R and my guess is
that I'm missing something into the above R function.
Cheers
Armel
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