[R] cut - suggestion

[BXC (Bendix Carstensen)]

I often use cut in order to produce quick tabulations of continuous data.
But if you choose "sensibe cotpoints as in:

> z <- rnorm(100)
> table( cut( z, breaks=seq(-1,1,0.5) ),
+ cut( z, breaks=c(-100,0,100) ) )
           
            (-100,0] (0,100]
  (-1,-0.5]       18       0
  (-0.5,0]        19       0
  (0,0.5]          0      17
  (0.5,1]          0      19
 
you get labels that do not align properly.
Looking into cut this descends from the definition of the labels:

            ch.br <- formatC(breaks, dig = dig, wid = 1)

i.e. really from the default of the format-agrument of formatC, which 
is "g" (significant digits). Inside formatC is namely:

if (missing(format) || is.null(format)) 
        format <- if (mode == "integer") 
            "d"
        else "g"

Significant digtits do not align properly and makes things difficult to
read,
so i sugget that a `,format="f"' be added in the definition of ch.br in
cut.

----------------------
Bendix Carstensen
Senior Statistician
Steno Diabetes Centre
Niels Steensens Vej 2
DK-2820 Gentofte
Denmark
tel: +45 44 43 87 38
mob: +45 28 25 87 38
fax: +45 44 43 73 13
bxc at novonordisk.com
www.biostat.ku.dk/~bxc
----------------------


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