[R] R does not recognise columns and rows as they are supposed to be

[William Dunlap]

> >           X<-c(364:369) ; Y<-c(82:92) #####   for sellected region
> >           ...
> >          file2<-matrix(data=file,ncol=720,nrow=360)
> > 	extract[i]<-mean(file2[X,Y],na.rm=TRUE)

Note that 2-dimensional subscripts are given as
    mat[ROWS, COLUMNS]
and you are using the reverse order, hence you get the
error message that you are asking for rows 364:369 of
a 360-row matrix.

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of Rui Barradas
> Sent: Thursday, May 24, 2012 9:48 AM
> To: r-help at r-project.org
> Subject: Re: [R] R does not recognise columns and rows as they are supposed to be
> 
> Hello,
> 
> There are several things with your code, most of which are not errors.
> 
> 1. X<-c(364:369) ; Y<-c(82:92 and later c(1:365)
> Expressions of the form m:n are integer sequences, the c() is not needed.
> 
> 2. extract<-vector()
> First you create the vector, then keep extending it throughout the loop.
> This is much slower.
> If you know the final length (and type), create it like this:
> extract <- numeric(365)   # or double(365)
> 
> 3. 'dir1' is not used.
> 
> 4. Now the readBin instruction:
> 4.1. 'file' is the name of a function, use, say, 'file1' instead.
> 4.2. Option 'signed' defaults to TRUE but it's only valid for integer types.
> 
> 5. And, maybe this is the problem, in R, doubles are 8 bytes, not 4. Get rid
> of option 'size', like the help page says,
> 
> "If size is specified and not the natural size of the object, each element
> of the vector is coerced to an appropriate type before being written or as
> it is read."
> 
> You are NOT reading doubles.

The file may well contain single precision numbers and using
  what="double", size=4
will read them and convert them to doubles so other functions
in R can use them.  (Likewise, readBin can read files containing
1- or 2-byte signed or unsigned integers and store them as the
4-byte signed integers that the rest of R can deal with.)

If the file was created on another sort of machine, then you may
have worry about the byte order - try adding endian="big" or
endian="little".

> 
> As for the rest, it seems ok to me. (Keep option 'n' in readBin.)
> 
> Hope this helps,
> 
> Rui Barradas
> 
> Jonsson wrote
> >
> > Dear All,
> > The code given bellow is to extract  values of one region and write that
> > to a text file(there are 365 binary files in the directory).
> > The problem which I am facing is that all my files are binary with size of
> > 360 rows and 720 columns.
> > I specified that in this line:
> > file2<-matrix(data=file,ncol=720,nrow=360) but I got an error : Error in
> > mean(file2[X, Y], na.rm = TRUE) : subscript out of bounds.
> > and then I rewrote the above line as
> > :file2<-matrix(data=file,ncol=360,nrow=720.I put ncol=360 and nrows =720
> > which is not right.But that worked and I didn't get any error.however,the
> > results were not correct.
> > Any help please
> >              X<-c(364:369) ; Y<-c(82:92) #####   for sellected region
> >                 extract<-vector()
> > dir1<- list.files("C:\\Users\\aalyaari\\Desktop\\New folder
> > (10)\\Climate_Rad_f_GAMMA_%d.img", full.names = TRUE)
> > listfile<-dir()
> > for (i in c(1:365)) {
> >       conne <- file(listfile[i], "rb")
> >       file<- readBin(conne, double(), size=4,  n=720*360, signed=T)
> >      file2<-matrix(data=file,ncol=720,nrow=360)
> > 	extract[i]<-mean(file2[X,Y],na.rm=TRUE)
> >       close(conne)
> > write.table(extract,"C:\\Users\\aalyaari\\Desktop\\New folder
> > (10)\\sam.txt")}
> >
> 
> 
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