[R] R help for a newby

[ben@zoo.ufl.edu]

  I don't actually think there's an easy way to do this; an alternate way
might be to reformat your data either with fixed-width fields (read.fwf())
or with separator characters.  If you insist, though, here is a (probably
overly convoluted) way of doing what I think you want.  I would welcome
suggestions for making this more efficient or understandable.

scan.irreg <- function(...) {
  row.lens <- count.fields(...)  # count fields per line
  x <- scan(...)                  # read data into a vector
  maxcol <- max(row.lens)        # largest # of columns
  nrows <- length(row.lens)      # total # of rows
  y <- matrix(nrow=nrows,ncol=maxcol)
  ind1 <- seq(1,length=nrows,by=maxcol)
  ind2 <- cbind(ind1,ind1+row.lens-1)
  ind3 <- unlist(apply(ind2,1,function(x)seq(from=x[1],to=x[2])))
  ty <- t(y)
  ty[ind3] <- x
  t(ty)
}

  Arguably it would be more efficient and more "R-like" (and certainly
easier to code) to return the answers as a list of variable-length
vectors:

scan.irreg2 <- function(...) {
  row.lens <- count.fields(...)  # count fields per line
  x <- scan(...)                  # read data into a vector
  nrows <- length(row.lens)      # total # of rows
  split(x,rep(1:nrows,row.lens))
}

  You can then use apply or sapply to operate on the elements of the list.

On Mon, 13 Nov 2000, Thomas Likins wrote:

> Hello,
> 
> 	Yesterday I asked a question about how to read data from a file
> that had test numbers in the first column followed by 4 readings. I received
> three responses to my question with in an hour. Thanks to all who responded.
> After trying out your responses - which seem to work. I noticed that some of
> the data had only one or two reading after the test number. 
> 
> 	My next question: what's the command to fill a matrix with an unknown
> value of column data. The nice people who responded to me yesterday used
> matrix(scan("data.file"),rcol=5, byrow=TRUE). I would have to imagine the
> solution is some variation on this theme. I tried several last night
> myself, but 
> with no success.  I hope that you will bear with me though  this leaning curve.
> I HAVE tried to read the documentation, but there is so much information that
> it's some what overwhelming. I'm sure all of you  know how important it
> is to be able to succeed in using a new tool to prevent being frustrated and 
> giving up prematurely. I am truly in awe over this tool, its power is
> amazing.  
> I hope you will bear with me as I continue in the mastery of this incredible
> tool.
> 
> 	Thanks for all your help,
> 
> 	Tom Likins
> 	
> 
> 
> 
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-- 
318 Carr Hall                                bolker at zoo.ufl.edu
Zoology Department, University of Florida    http://www.zoo.ufl.edu/bolker
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