On Apr 7, 2011, at 3:09 PM, Dmitry Berman wrote:
Listers,
I have a question regarding correlation matrices. It is fairly
straight
forward to build a correlation matrix of an entire data frame. I
simply use
the command cor(MyDataFrame). However, what I would like to do is
construct
a smaller correlation matrix using just three of the variable out of
my data
set.
When I run this:
cor(MyDataFrame$variable1, MyDataFrame$variable2,MyDataFrame
$variable3) I
get an error.
But you choose not to offer it. Why is that?
Is there a way to do this through a built in function or is this
something I
have to construct manually?
Neither. You need to learn how R does argument matching:
From help(cor)
"Usage:
cor(x, y = NULL, use = "everything", method = c("pearson", "kendall",
"spearman"))"
So your 3 unnamed arguments were matched by position to `x`, `y` and
`use`.
Try cor(x = myDataFrame[, c("variable1", "variable2", "variable3")]
--
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
