On 05/10/2012 8:19 AM, Berry Boessenkool wrote:
Hi all,
I improved a function drawing horizontal histograms (code below) which uses
barplot and works fine.
It does,however, need to assign a function to the global environment to later
find the actual location on the vertical axis, and not the number of bars used
by barplot.
Hopefully, running the examples below will illustrate that.
As said, it works perfectly fine and does exactly what I want.
The problem arises now that I'm building a package (just for myself, for now)
and run into R CMD
check telling me 'no visible binding for '<<-' assignment'.
(wording below)
Similar problem as in
http://r.789695.n4.nabble.com/R-CMD-check-tells-me-no-visible-binding-for-global-variable-what-does-it-mean-td1837236.html
My question is:
Is there a way to avoid assigning the function to the global environment with
<<- but still have it available? I know it is generally not good practice.
You can return the function as the value of your function. A bonus:
if it is created within the body of your function, it will have access
to all the local variables there.
You shouldn't write to the global environment, because globalenv belongs
to the user, not to you. If the user wants your function in the global
environment s/he can just assign the value of your function to a
variable there.
Duncan Murdoch
Or ist it OK in a case like this, and is there a way to avoid the notes from
the rcmd check (make the function package-compatible)?
Or should I just ignore these notes? (I'm completely new to building packages
and cannot judge the importance yet.)
I'd be very thankful for any hints!
Berry
PS: I recently read about barcharts in lattice, but by now I'm already used to
my function. (And I learned a lot writing it a couple of years ago).
# Function
horiz.hist <- function(Data, breaks="Sturges", col="transparent", las=1,
ylim=range(HBreaks), labelat=pretty(ylim), labels=labelat, border=par("fg"),
... )
{a <- hist(Data, plot=FALSE, breaks=breaks)
HBreaks <- a$breaks
HBreak1 <- a$breaks[1]
hpos <<- function(Pos) (Pos-HBreak1)*(length(HBreaks)-1)/
diff(range(HBreaks)) # Assign a function to the global environment with values
calculated inside the main function.
barplot(a$counts, space=0, horiz=T, ylim=hpos(ylim), col=col,
border=border,...)
axis(2, at=hpos(labelat), labels=labels, las=las, ...)
print("use hpos() to address y-coordinates") }
# Data and basic concept
set.seed(8); ExampleData <- rnorm(50,8,5)+5
hist(ExampleData)
horiz.hist(ExampleData, xlab="absolute frequency")
# Caution: the labels at the y-axis are not the real coordinates!
# abline(h=2) will draw above the second bar, not at the label value 2. Use
hpos:
abline(h=hpos(11), col=2)
# Further arguments
horiz.hist(ExampleData, xlim=c(-8,20))
horiz.hist(ExampleData, main="the ... argument worked!", col.axis=3)
hist(ExampleData, xlim=c(-10,40)) # with xlim
horiz.hist(ExampleData, ylim=c(-10,40), border="red") # with ylim
horiz.hist(ExampleData, breaks=20, col="orange")
axis(2, hpos(0:10), labels=F, col=2) # another use of hpos()
# One shortcoming: doesn't work with breakpoints provided as a vector with
different widths of the bars
Wording from the rcmd check when building a package:
* checking R code for possible problems ... NOTE
horiz.hist: no visible binding for '<<-' assignment to 'hpos'
horiz.hist: no visible global function definition for 'hpos'
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and provide commented, minimal, self-contained, reproducible code.