[R] trouble with data.matrix

Martin Maechler
2001-10-27T13:29:58Z

>>>>> "Laurent" == Laurent Gautier <laurent at
cbs.dtu.dk> writes:

    Laurent> Dear all, The following causes me trouble:

	> a <- data.frame(2:5,3:6,4:7)

	> str(a)
	`data.frame':	4 obs. of  3 variables:
	 $ X2.5: int  2 3 4 5
	 $ X3.6: int  3 4 5 6
	 $ X4.7: int  4 5 6 7

	> str(data.matrix(a))
	 int [1:4, 1:3] 2 3 4 5 3 4 5 6 4 5 ...
	 - attr(*, "dimnames")=List of 2
	  ..$ : chr [1:4] "1" "2" "3" "4"
	  ..$ : chr [1:3] "X2.5" "X3.6" "X4.7"

    Laurent> Reading the man page for 'data.matrix' trends to
indicate it
    Laurent> generates a numerical matrix from a data.frame.

exactly --- and what is the trouble ?
You *did* get a numerical matrix {integers are numeric}

    Laurent> ... or am I wrong ? (I could almost swear it was working
    Laurent> before...

(still is)

Martin Maechler <maechler at stat.math.ethz.ch>
http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO D10	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><
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