From: Mayeul KAUFFMANN <mayeul.kauffmann_at_tiscali.fr>

Date: Thu 16 Sep 2004 - 22:33:15 EST

If you want to do the conversions as you say, you should be calling data.matrix.

R-devel@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-devel Received on Thu Sep 16 22:49:07 2004

Date: Thu 16 Sep 2004 - 22:33:15 EST

On Thu, 16 Sep 2004, Mayeul KAUFFMANN claimed:

> ?cor says it accepts data.frame. In fact, it does iff they have no (or

It actually says

x: a numeric vector, matrix or data frame. ^^^^^^^

If you want to do the conversions as you say, you should be calling data.matrix.

@@@@@@@@@@@@@@@@@@@@@@@@

Thanks a lot !!!

When reading it first , I mistranslated it in my mind in a phrase that
would mean

"a numeric vector, a matrix or a data frame." (I'm not a native English
speaker). Sorry for all that stuff....

*But* let's admit that the two followings are not treated identically:
cor(x[,4],x[,5])

cor(x[,4:5])

in the first case, the non-numeric vector is transformed to a numeric one
in the second case, the (partially) non-numeric dataframe is not
transformed to a numeric one

To be more exact,

the doc should not say

x: a numeric vector, matrix or data frame. ^^^^^^^ but x: a vector that can be coerced to numeric, a numeric matrix or a numeric data frame. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^ ^^^^^^^

Cheers,

Mayeul

PS:

by the way, if someones changes the doc,
the claim 'The default is equivalent to 'y = x' (but more efficient).'
is inexact as evidenced by the following:
X <- (data.frame(x=rep(1,5),y=1:5))

> cor(X,X)

x y

x NA NA

y NA 1

Warning message:

The standard deviation is zero in: cor(x, y, na.method, method ==
"kendall")

> cor(X)

x y

x 1 NA

y NA 1

Warning message:

The standard deviation is zero in: cor(x, y, na.method, method ==
"kendall")

R-devel@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-devel Received on Thu Sep 16 22:49:07 2004

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