On 2010-04-09 10:04, Dieter Menne wrote:
RockO wrote:
I tried to find a solution in the search list, but I cannot find it. I
would like to read a .txt file with, let say, three variables, with two of
which have repeated values in a number a columns.
The variables: Treat, x1, x2.
The values:
A 2.5 3.4 2.7 5.6 5.7 5.4 10.1 9.4 ...
B 5.3 5.4 6.5 7.5 1.3 4.5 10.5 4.1 ...
...
In the first column, the letters represent the variable "Treat", and the
sequence of numbers on a same line represent pairs of values for "x1" and
"x2".
Looks like SAS is quite elegant here (don't kill me, I could not afford
using SAS, R has save my retirement fund).
I would first read it in "as usual", and do the reformatting later.
library(reshape)
wide = read.table("wideseq.txt",sep=" ")
# renames columns
names(wide) = c("varname",rep(c("x1","x2"),ncol(wide)%/%2))
str(wide)
melt(wide)
Now you have the long format, which is not exactly what you want, but
typically much more useful in R than the format you require. You might use
one of the function in package reshape to get your format.
Almost. But you're a bit too clever with the names() because
melt() will just re-read the first x1, x2 values.
wide <- as above ...
dm <- melt(wide)
# replace dm$variable with appropriate factor
dm$variable <- gl(2, 2, nrow(dm), c('x1','x2'))
# choose names for columns
names(dm) <- c('Treat', 'x', 'value')
I agree that this 'long' format is usually most useful for
further analysis.
-Peter
--
Peter Ehlers
University of Calgary
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