[R] quantmod's addTA plotting functions

[P Ehlers]

On 2011-05-05 0:47, Russ Abbott wrote:
> Hi,
>
> I'm having trouble with quantmod's addTA plotting functions.  They seem to
> work fine when run from the command line. But when run inside a function,
> only the last one run is visible.  Here's an example.
>
>
> test.addTA<- function(from = "2010-06-01") {
>      getSymbols("^GSPC", from = from)
>      GSPC.close<- GSPC[,"GSPC.Close"]
>      GSPC.EMA.3<- EMA(GSPC.close, n=3, ratio=NULL)
>      GSPC.EMA.10<- EMA(GSPC.close, n=10, ratio=NULL)
>      chartSeries(GSPC.close, theme=chartTheme('white'), up.col="black",
> dn.col="black")
>      addTA(GSPC.EMA.3,   on = 1, col = "#0000ff")
>      addTA(GSPC.EMA.10,  on = 1, col = "#ff0000")
>      # browser()
> }
>
>
> When I run this, GSPC.close always appears.  But only GSPC.EMA10 appears on
> the plot along with it. If I switch the order of the addTA calls,
> only GSPC.EMA3 appears. If I uncomment the call to browser() neither appears
> when the browser() interrupt occurs. I can then draw both GSPC.EMA.3 and
> GSPC.EMA10 manually, and let the function terminate. All intended plots are
> visible after the function terminates. So it isn't as if one wipes out the
> other. This shows that it's possible to get all three lines on the plot, but
> I can't figure out how to do it without manual intervention. Any suggestions
> are appreciated.

Perhaps you didn't see this NOTE on the ?TA help page:

"Calling any of the above methods from within a function
or script will generally require them to be wrapped in a
plot call as they rely on the context of the call to
initiate the actual charting addition."

Peter Ehlers

>
> Thanks.
>
> *-- Russ *
>
> 	[[alternative HTML version deleted]]
>
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