Thanks a lot, James!!
The problem is fixed. On the version 1.4.0 Mac/darwin (the latest
available version for this system) the function read.table (which is
called from read.delim etc., too) has the bug you explained.
Inserting the row
nlines <- nlines+1
after
lines <- c(lines, line)
removes this bug.
M.
On Friday, February 22, 2002, at 02:33 PM, james.holtman at convergys.com
wrote:
If you can not the the latest 1.4.1, here is a patch (adds one line to
read.table) that will fix it on your current system.
The 'read.table' function appears to be up to 10X slower in R 1.4.0
than
1.3.1 for some of the data sets I read in. I was comparing the source
for the 2 versions and see that it was rewritten in R 1.4.0.
I think I found out what part of the problem might be. I was
comparing
R1.3.1 and R1.4.0 code and it appears that a statement is missing in
some
of the code for R 1.4. This is the section of code at the beginning
of
read.table. The loop starting with 'while (nlines < 5)' will read in
the
entire file, because there is no increment of 'nlines' in the loop. I
traced through the code and this is what was happening. It then
does a
'pushBack' of the entire file. In tracing through the code, this is
is appears to be taking the time. With the change noted below, the
speed
was similar to R 1.3.1 and the results were the same.
Here is the current code with what I think is the additional statement
needed:
=================part of read.table========
nlines <- 0
lines <- NULL
while (nlines < 5) {
line <- readLines(file, 1, ok = TRUE)
if (length(line) == 0)
break
if (blank.lines.skip && length(grep("^[ \\t]*$", line)))
next
if (length(comment.char) && nchar(comment.char)) {
pattern <- paste("^[ \\t]*", substring(comment.char,
1, 1), sep = "")
if (length(grep(pattern, line)))
next
}
lines <- c(lines, line)
#
# additional line required
#
nlines <- nlines+1
}
Meinhard Ploner <meinhardploner at gmx.net> on 02/22/2002 03:17:34
To: james.holtman at convergys.com
cc:
Subject: Re: [R] read.table on Mac OS X, CARBON vs. DARWIN
Yes. Thanks a lot.
I had the 1.4.0 because on Fink the latest version (1.4.1) is not
available. However, I will download it from the CRAN.
Meinhard
On Thursday, February 21, 2002, at 10:29 PM,
james.holtman at convergys.com wrote:
read.table did have a bug in it in 1.4.0. It was fixed in 1.4.1. Is
that
what you are running with?
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