[R] drop zero slots from table?

[William Dunlap]

Here is one way:

> sorted.table <- function(x, name = if (is.list(x))names(x) else deparse(substitute(x))[1]) {
+    tab <- table(x)
+    names(dimnames(tab)) <- name
+    tab <- tab[tab > 0]
+    sort(tab, decreasing=TRUE)
+ }
> digits <- factor(trunc(100*log2(1:20)%%.1), levels=0:9)
> sorted.table(digits)
digits
0 8 2 6 4 5
9 4 3 2 1 1
> sorted.table(data.frame(DigitsColumn=digits))
DigitsColumn
0 8 2 6 4 5
9 4 3 2 1 1
> sorted.table(digits, name="My Digits")
My Digits
0 8 2 6 4 5
9 4 3 2 1 1

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of Sam Steingold
> Sent: Wednesday, September 19, 2012 9:13 AM
> To: r-help at r-project.org
> Subject: Re: [R] drop zero slots from table?
> 
> Function
> --8<---------------cut here---------------start------------->8---
> sorted.table <- function (vec) {
>   tab <- table(vec)
>   tab <- tab[tab > 0]
>   sort(tab, decreasing=TRUE)
> }
> --8<---------------cut here---------------end--------------->8---
> does what I want but it prints "vec" instead of the name of its
> argument:
> --8<---------------cut here---------------start------------->8---
> > sorted.table(foo$bar)
> vec
>   A  B
>   10 3
> --8<---------------cut here---------------end--------------->8---
> how do I pass all arguments of sorted.table() on to table() as is?
> thanks!
> 
> > * Sam Steingold <fqf at tah.bet> [2012-09-19 11:51:08 -0400]:
> >
> > I find myself doing
> > tab <- table(...)
> > tab <- tab[tab > 0]
> > tab <- sort(tab,decreasing=TRUE)
> > all the time.
> > I am wondering if the "drop 0" (and maybe even sort?) can be effected by
> > some magic argument to table() which I fail to discover in the docs?
> > Obviously, I could use droplevels() to avoid 0 counts in the first
> > place, but I do not want to drop the levels in the data.
> 
> --
> Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
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