On 2011-03-09 07:53, Richard and Barbara Males wrote:
Thank you for your prompt reply, I apologize for posting as an R
Commander question. Your response is pointing me in the right
direction, but I am still not quite there. The triangle package has
a qtriangle and dtriangle. The formal arguments are a, b, and c.
(formals(qtriangle)) When I use R Commander as:
qqPlot(Transfer5000$Transfer.Rate, dist="triangle", a=3000,b=5000,c=4000)
I get the error message:
Error in qqPlot.default(Transfer5000$Transfer.Rate, dist = "triangle", :
argument 5 matches multiple formal arguments
and I am unclear as to how to specify that the "c" argument needs to
pertain specifically to the qtriangle (or perhaps dtriangle) function
arguments, that is, how to avoid a conflict with other arguments of
qqPlot that are ambiguous when passed "c"..
Again, sorry to post here, as this has clearly wandered into other
territory. My exploratory searches to resolve this take me well
beyond my current ability in R. If there is not an obvious answer, I
will re-post specifically on the topic of specifying formal arguments
of distributions to qqPlot.
Dick,
I think that the author of the triangle package has chosen
an unfortunate name for one of the parameters. Here's a
work-around:
## define two new functions dtri() and qtri():
dtri <- function(q, a=0, b=1, cc=.5) dtriangle(q, a, b, cc)
qtri <- function(p, a=0, b=1, cc=.5) qtriangle(p, a, b, cc)
## now use "tri" as the distribution to pass to qqPlot:
qqPlot(x, "tri", a=3000, b=5000, cc=4000)
Peter Ehlers
Thanks.
Dick Males
On Tue, Mar 8, 2011 at 11:19 AM, John Fox<j...@mcmaster.ca> wrote:
Dear R. Males,
This isn't really an R Commander question, since the qqPlot() function is in
the car package and is just invoked by the R Commander.
From ?qqPlot: "distribution: root name of comparison distribution - e.g.,
"norm" for the normal distribution ... Any distribution for which quantile
and density functions exist in R (with prefixes q and d, respectively) may
be used." Thus, if there's a qtriangle() and dtriangle(), I suppose that you
should be able to get a QQ plot. Further from ?qqPlot: " ... arguments
such as df to be passed to the appropriate quantile function." Thus, you
should *name* the arguments to be passed to qtriangle() -- perhaps (of
course, you should use the correct names) min=3000, max=5000, mode=4000.
I hope this helps,
John
--------------------------------
John Fox
Senator William McMaster
Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
On Behalf Of Richard and Barbara Males
Sent: March-08-11 10:49 AM
To: r-help@r-project.org
Subject: [R] R Commander QQ Plot with triangular distribution
I am attempting to use the R Commander Graphs Quantile-Comparison
functionality on a dataset, to compare with a triangular distribution.
I have the package triangle. My question is on the syntax of how
to specify the parameters of the theoretical distribution in the
Parameters field of the dialog box. For example, the theoretical
distribution has min of 3000, max of 5000, mode of 4000. When I
enter this info as 3000,5000,4000 in the parameters field, I get:
qqPlot(EmpiricalData$Value, dist="triangle", 3000,5000,4000)
it produces a plot, but I am not sure that this is correct.
I have searched for examples, not found anything. Any help much
appreciated.
R. Males
Cincinnati, Ohio, USA
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