Re: [Rd] man page for as.matrix for data frames outdated?

From: Bill Dunlap <bill_at_insightful.com>
Date: Fri 03 Nov 2006 - 19:52:21 GMT

On Fri, 3 Nov 2006, Herve Pages wrote:

> > df5 <- data.frame(toto=c("a","bb"), titi=c(9,999))
> > as.matrix(df5)
> toto titi
> 1 "a" " 9"
> 2 "bb" "999"
> ...
> 2) the questionable decision to do this conversion using 'format'
> (leading to the addition of unnecessary white space) and not
> simply 'as.character'

It is possible that this decision was made because one use of as.matrix(mixed-mode-data-frame) was for printing data.frames and format(numberic-column) would line up the decimal points and make one scientific-notation/or-not decision for the entire column. (Splus3.4, c. 1996, printed data.frames with print(as.matrix(x)), but by 1999 Splus4.7 was using print(format(x)).)

   R> df6<- data.frame(toto=c("a","bb","ccc"), titi=c(.9e-20,.99999,999.9))    R> as.matrix(df6)
     toto titi

   1 "a"   "9.0000e-21"
   2 "bb"  "9.9999e-01"
   3 "ccc" "9.9990e+02"

   R> df7<-data.frame(toto=c("a","bb","ccc"), titi=c(.9,.99999,999.9))    R> as.matrix(df7)
     toto titi
   1 "a"   "  0.90000"
   2 "bb"  "  0.99999"
   3 "ccc" "999.90000"

Once such a decision is made it is hard to change things, especially when the benefit is slight.



Bill Dunlap
Insightful Corporation
bill at insightful dot com
360-428-8146

 "All statements in this message represent the opinions of the author and do  not necessarily reflect Insightful Corporation policy or position."



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