R help - Feb 2012 - object not found - Can not figure out why I get this error: Error in NROW(yCoordinatesOfLines) : object 'low' not found

Hi,

I have been using R for over a year now. I am a very happy user. Thank you
for making this happen.

This is my first question to this list.

I trying to add some functions to quantmod that would enable me to draw
arbitrary lines and text and make sure they are redrawn. I have created
following function:

require(quantmod)

# Add horizontal line to graph produced by quantmod::chart_Series()
add_HorizontalLine<-function(yCoordinatesOfLines, on=1, ...) {
    lenv <- new.env()
    lenv$add_horizontalline <- function(x, yCoordinatesOfLines, ...) {
        xdata <- x$Env$xdata
        xsubset <- x$Env$xsubset

        x0coords <- rep(1, NROW(yCoordinatesOfLines))
        x1coords <- rep(NROW(xdata[xsubset]), NROW(yCoordinatesOfLines))

        if ((NROW(x0coords) > 0) & (NROW(x1coords) > 0)) {
            segments(x0coords,
                     yCoordinatesOfLines,
                     x1coords,
                     yCoordinatesOfLines, ...)
#            abline(h=yCoordinatesOfLines, ...)
        }
    }
    mapply(function(name, value) {assign(name,value,envir=lenv)},
names(list(yCoordinatesOfLines=yCoordinatesOfLines,...)),
list(yCoordinatesOfLines=yCoordinatesOfLines,...))
    exp <- parse(text=gsub("list","add_horizontalline",
as.expression(substitute(list(x=current.chob(),

yCoordinatesOfLines=yCoordinatesOfLines, ...)))), srcfile=NULL)
    plot_object <- current.chob()
    lenv$xdata <- plot_object$Env$xdata
#    plot_object$set_frame(sign(on)*abs(on)+1L)
    plot_object$set_frame(2*on)
    plot_object$add(exp,env=c(lenv, plot_object$Env),expr=TRUE)
    plot_object
}

# Short test function that uses add_HorizontalLine
test<-function(series, low=20, high=80) {
    chart_Series(SPX, subset="2012")
    add_TA(RSI(Cl(SPX)))
    plot(add_HorizontalLine(c(low, high), on=2, col=c('green',
'red'),
lwd=2))
}

# Actual test
SPX <- getSymbols("^GSPC", from="2000-01-01",
auto.assign=FALSE)
dev.new()
test(SPX)

This gives me the following error:
> test(SPX)
Error in NROW(yCoordinatesOfLines) : object 'low' not found

What am I doing wrong here? Any hints highly appreciated.

The funniest thing is that this was working and somehow broke it...

Best,
Samo

	[[alternative HTML version deleted]]

Ah, scoping rules...
Consider:
f <- function(x,...) plot(x,xlim=c(low,high),...)
f(1:10,low=2,high=9)  # "Error ...  object 'low' not found "

But:

f <- function(x,low,high,...) plot(x,xlim=c(low,high),...)
f(1:10,2,9,col=2)  # beautiful red points [low,high]

Sorry I can't be more specific but never heard of quantmod.
Hope this helps anyway.


On Sat, Feb 11, 2012 at 7:43 AM, Samo Pahor <samo.pahor at gmail.com>
wrote:
> Hi,
>
> I have been using R for over a year now. I am a very happy user. Thank you
> for making this happen.
>
> This is my first question to this list.
>
> I trying to add some functions to quantmod that would enable me to draw
> arbitrary lines and text and make sure they are redrawn. I have created
> following function:
>
> require(quantmod)
>
> # Add horizontal line to graph produced by quantmod::chart_Series()
> add_HorizontalLine<-function(yCoordinatesOfLines, on=1, ...) {
> ? ?lenv <- new.env()
> ? ?lenv$add_horizontalline <- function(x, yCoordinatesOfLines, ...) {
> ? ? ? ?xdata <- x$Env$xdata
> ? ? ? ?xsubset <- x$Env$xsubset
>
> ? ? ? ?x0coords <- rep(1, NROW(yCoordinatesOfLines))
> ? ? ? ?x1coords <- rep(NROW(xdata[xsubset]), NROW(yCoordinatesOfLines))
>
> ? ? ? ?if ((NROW(x0coords) > 0) & (NROW(x1coords) > 0)) {
> ? ? ? ? ? ?segments(x0coords,
> ? ? ? ? ? ? ? ? ? ? yCoordinatesOfLines,
> ? ? ? ? ? ? ? ? ? ? x1coords,
> ? ? ? ? ? ? ? ? ? ? yCoordinatesOfLines, ...)
> # ? ? ? ? ? ?abline(h=yCoordinatesOfLines, ...)
> ? ? ? ?}
> ? ?}
> ? ?mapply(function(name, value) {assign(name,value,envir=lenv)},
> names(list(yCoordinatesOfLines=yCoordinatesOfLines,...)),
> list(yCoordinatesOfLines=yCoordinatesOfLines,...))
> ? ?exp <-
parse(text=gsub("list","add_horizontalline",
> as.expression(substitute(list(x=current.chob(),
>
> yCoordinatesOfLines=yCoordinatesOfLines, ...)))), srcfile=NULL)
> ? ?plot_object <- current.chob()
> ? ?lenv$xdata <- plot_object$Env$xdata
> # ? ?plot_object$set_frame(sign(on)*abs(on)+1L)
> ? ?plot_object$set_frame(2*on)
> ? ?plot_object$add(exp,env=c(lenv, plot_object$Env),expr=TRUE)
> ? ?plot_object
> }
>
> # Short test function that uses add_HorizontalLine
> test<-function(series, low=20, high=80) {
> ? ?chart_Series(SPX, subset="2012")
> ? ?add_TA(RSI(Cl(SPX)))
> ? ?plot(add_HorizontalLine(c(low, high), on=2, col=c('green',
'red'),
> lwd=2))
> }
>
> # Actual test
> SPX <- getSymbols("^GSPC", from="2000-01-01",
auto.assign=FALSE)
> dev.new()
> test(SPX)
>
> This gives me the following error:
>> test(SPX)
> Error in NROW(yCoordinatesOfLines) : object 'low' not found
>
> What am I doing wrong here? Any hints highly appreciated.
>
> The funniest thing is that this was working and somehow broke it...
>
> Best,
> Samo
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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