scales percent precision

But percent_format() does not take the argument, multiply it by 100, and 
paste on a percent sign, as we see here:

?scales::percent_format
percent_format(0.0101010101)

Error in percent_format(0.0101010101) : unused argument(s) (0.0101010101)

args(percent_format)

function () NULL

And how do we control the significant digits when we use percent()?

percent(0.0101010101)

[1] "1.01%"

My point is that

?scales::percent_format

does not answer these questions. This is what I mean by saying that the 
function is not documented.

On 2014-02-27 Thu 14:34, Dennis Murphy wrote:

Hi:

On Thu, Feb 27, 2014 at 8:49 AM, Jacob Wegelin <jacobwegelin at fastmail.fm> 
wrote:

scales::percent appears not to be documented.

?scales::percent_format

where it tells you that it takes its argument, multiplies it by 100
and then attaches a percent sign to it. For most situations, the data
should be relative frequencies/proportions. BTW, many of the functions
in the scales package are second-order R functions, which means there
are two calls in the function invocation. The first call returns a
function and the second is a call to the returned function.

Details:

At http://cran.r-project.org/web/packages/scales/scales.pdf, equivalently 
in
?percent, I find no answer to the following two questions.

(1) How can I specify the number of decimal points in a call to percent()?
For instance, 0.010101 could be

1%

1.0%

1.01%

etc. depending on what kind of report I'm writing.

I can control precision myself by writing

mypercent<-function(theargument, siglevel=2) {
        stopifnot(is.numeric(theargument))
        paste(signif(theargument, siglevel) * 100, "%", sep="")
}

and then we have

mypercent(0.010101)

[1] "1%"

mypercent(0.010101, 5)

[1] "1.0101%"

mypercent(0.010101, 3)

[1] "1.01%"

percent_format() uses pretty breaks by default, so you'd probably want
to pass your desired labels to scale_y_continuous() directly and avoid
percent_format(). You could call the function on a vector of breaks
and use the return values for the labels.

(2) What is the function precision() inside percent()? I find no
documentation for it, and in fact it does not appear in the search path. 
Nor
does round_any().

round_any() comes from the plyr package. I have no idea where
precision() comes from; I've wondered about that myself a couple of
times. I imagine it comes from one of the imported packages, but I
didn't find it in any of plyr, stringr or labeling. I didn't check the
color-related packages (RColorBrewer, dichromat or munsell). It could
also be a hidden function.

Dennis

percent(0.010101)

[1] "1.01%"

percent

function (x) {
    x <- round_any(x, precision(x)/100)
    str_c(comma(x * 100), "%")
}
<environment: 0x10c0f9350>

find("precision")

character(0)

find("round_any")

character(0)

Thanks for any insights

Jacob Wegelin

sessionInfo()

R version 2.15.3 (2013-03-01)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
 [1] tools     grid      splines   stats     graphics  grDevices utils
datasets  methods   base

other attached packages:
[1] scales_0.2.3    xtable_1.7-0    reshape2_1.2.2  moments_0.13
corrplot_0.70   ggplot2_0.9.3.1 nlme_3.1-108

loaded via a namespace (and not attached):
 [1] colorspace_1.2-0   dichromat_1.2-4    digest_0.6.0       gtable_0.1.2
labeling_0.1       lattice_0.20-13    MASS_7.3-23        munsell_0.4
 [9] plyr_1.8           proto_0.3-10       psych_1.2.8
RColorBrewer_1.0-5 stringr_0.6.2