On Wed, 2005-02-02 at 13:54 +1300, Brett Stansfield
wrote:> can you tell me how to ask R to analyse a subset of data
>
> eg. supposing the data set consists of 9 columns and I only want R to
> analyse columns 1, 3 and 5
>
> how would I command R to conduct eg. boxplots of those variables only?
#Create a matrix with 9 columns
mat <- matrix(rnorm(90), ncol = 9)
# create a boxplot from cols 1,3 and 5
boxplot(data.frame(mat[, c(1, 3, 5)]))
In this case, passing the 3 columns of the matrix as a data frame
enables boxplot() to plot the 3 columns in a single call. There is an
example of this in ?boxplot.
You might also want to review the help for extracting sections of multi-
dimensional objects:
?Extract or ?"["
and the examples therein.
HTH,
Marc Schwartz