Roger Harbord
I've encountered some strange behaviour in Nick Cox's
program -distplot-
published in STB-51. It won't let me plot the distribution
functions of
more than one variable AND use another variable to label
the points,
although I can do either alone.
I'll use the automobile data to demonstrate so others can
try to replicate
the problem, although there's little purpose to the
commands in this
context - with my real data I'm comparing two distributions
graphically and
hoped to label the points so I can identify outliers at the
same time
(mainly for presentation purposes):
-------------------------------------------
. use "C:\Program Files\StataSE\auto.dta"
(1978 Automobile Data)
. distplot length, c(J) s([rep78])
. * (worked fine)
. distplot length displacement, c(JJ) s(oo)
. * (also worked fine)
. distplot length displacement, c(JJ) s([rep78]o)
variable rep78 not found
r(111);
. * Just to check I've got the syntax right in the s() option :
. graph length displacement weight, c(JJ) s([rep78]o)
. * (worked fine though a mess of a graph!)
. * describe my setup :
. which distplot
c:\ado\stbplus\d\distplot.ado
*! version 1.5.0 NJC 24 March 1999 [STB-51: gr41]
Anyone any idea what's going wrong here? That error
message seems most
bizarre to me - how can Stata suddenly not be able to find rep78 ??
No mystery here: although this behaviour is not
documented, it is a straightforward consequence
of the method used, as may be seen by looking at
the code.
-distplot- temporarily -preserve-s and then restructures
the data when you want a plot of more than one variable.
The rationale for doing this was, presumably, to allow
a plot of more than 20 variables. Occasionally one has
a large bundle of variables all of the same kind and
it is desired to see a spaghetti plot showing their
collective pattern.
The side-effect, however, is that some variables in the
data set may disappear from sight while the graph is being produced.
A work-around would be for me to add an option specifying
variables which must be carried along, or for me to
parse the -sy()- argument and automatically identify
variables which the user clearly needs for the purpose.
I'll put that on a to-think-about list.
Nick
[email protected]
So a possible work-around for users such as me in the meantime would be to :
