I would phrase this in terms of text labels.
Ulrich Kohler has written an -egen- function -gmlabvpos-
using another approach to this problem, which is
downloadable from SSC.
Nick
[email protected]
RJ Harris
> Have been having a problem of my own with the above as I'm
> often getting
> groups of observations clustered together. The way I thought
> to deal with
> this is to use the mlabvposition() option so that a variable
> can be used to
> set the position of the label on a clock face.
>
> Of course, this is rather tedious to set by hand, so the
> solution I came up
> with was to do a cluster analysis on the co-ordinates so they're in
> sensible groups, then do some trigonometry to set the clock
> positions such
> that labels are spread out around each group of observations.
> It doesn't
> work perfectly and takes a bit of fiddling with cluster sizes
> sometimes,
> but might be worth a try. I don't know if anyone's had a go at this
> approach before and already done a far better job, but here
> is some example
> code:
>
>
> gen temp = _N/5
> recast int temp, force
> replace temp = 1 if temp == 0
> local num = temp
> drop temp
>
> cluster kmeans x y, k(`num') gen(clNo)
> summ clNo
> local max = r(max)
> gen xx = .
> gen yy = .
>
> forvalues i = 1/`max'{
> summ x if clNo == `i'
> replace xx = x-r(mean) if clNo == `i'
> summ y if clNo == `i'
> replace yy = y-r(mean) if clNo == `i'
>
> replace xx = 1 if xx == 0 // some clusters only 1 obs
> replace yy = -1 if yy == 0
> }
>
> gen clockVar = .
> replace clockVar = 3-12*atan(yy/2*xx)/(2*_pi) if xx > 0 & yy > 0
> replace clockVar = 3-12*atan(yy/2*xx)/(2*_pi) if xx > 0 & yy < 0
> replace clockVar = 9-12*atan(yy/2*xx)/(2*_pi) if xx < 0 & yy < 0
> replace clockVar = 9-12*atan(yy/2*xx)/(2*_pi) if xx < 0 & yy > 0
> recast int clockVar, force
> replace clockVar = 12 if clockVar == 0
> sort clNo clockVar
> list
>
> scatter y x, mlabel(name) mlabvposition(clockVar)
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