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Re: st: Problems with -triplot-
Friedrich Huebler <email@example.com>
Re: st: Problems with -triplot-
Fri, 6 Feb 2009 10:03:09 -0500
Many thanks for your help. I now have the graph that I wanted.
On Fri, Feb 6, 2009 at 9:39 AM, Nick Cox <firstname.lastname@example.org> wrote:
> triplot p q r, c(l l) mcolor(pink blue)
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org] On Behalf Of Nick Cox
> Sent: 06 February 2009 13:12
> To: email@example.com
> Subject: RE: st: Problems with -triplot-
> Thanks to Friedrich for his comments.
> Fortunately, I see no real problems here.
> The key to understanding -separate()- is laid out tersely in the help:
> "separate() indicates that observations are to be subdivided into
> classes according to a
> specified variable. A legend will be shown if and only if more
> than one class is so
> defined. Each class is plotted as if it defined a single
> Note that last sentence.
> To back up slightly, the one simple idea about -triplot- is that you
> feed it
> triplot p q r
> and it does some school student algebra (or trigonometry) to convert to
> that to a
> scatter y x
> together with extra bits and pieces that are of considerable cosmetic
> importance, but are nevertheless secondary to the logic.
> If you say -separate()-, -triplot- converts that (in your example) to a
> scatter y1 y2 x
> using no more than (surprise) the -separate- command. So you need to
> spell out
> scatter y1 y2 x, c(l l) mcolor(pink blue)
> or more precisely,
> triplot p q r x, c(l l) mcolor(pink blue)
> or whatever. Each class becomes a separate variable, and you apply
> standard -twoway- syntax to get the desired result.
> As for the -legend()-, -triplot- doesn't try to be smart about the
> legend but it does not have to be because you maintain full control of
> it. The default is indeed likely to be lousy. A better default would be
> legend(ring(0) pos(1) col(1))
> and perhaps I should wire that in. (Note the -legend()- pops up
> spontaneously only if -separate()- is issued, as indicated in the help.)
> If you are following along, you'll see that the way to get -triplot- to
> superimpose multiple sets of triangular coordinates is to -stack- or
> -reshape- to a long data structure with a grouping variable.
> Friedrich's questions have given me ideas for small improvements to your
> code and help.
> Friedrich Huebler
> To clarify my question, I would like to have separate lines, one line
> for each country.
> On Thu, Feb 5, 2009 at 4:54 PM, Friedrich Huebler <firstname.lastname@example.org>
>> Nick Cox recently announced an updated version of his -triplot-
>> package, available from SSC. I encountered some problems with the
>> I am trying to generate a graph similar to Figure 15 in Cox (2004),
>> but with data from two countries. I would like to connect the data
>> points for each country but when I draw the graph with the options
>> c(l) and separate(country), only the points from the first country are
>> connected. Is it possible to connect the points from the second
>> country, too? Can the appearance of the markers for the second country
>> be changed? Options like mcolor() only affect the markers for the
>> first country.
>> There is also a problem with the legend. At the default position below
>> the graph, the legend partly covers the label for the lower side of
>> the triangle.
>> Reference: Cox, Nicholas J. 2004. Speaking Stata: Graphing categorical
>> and compositional data. Stata Journal 4, no. 2: 190-215.
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