spmap: several observations per identifier; id() does not uniquely identify the observations;

[Nikolaj Tetz]

Hi,

I am currently trying to plot a map with several observations for each district (polygon, I guess), I am interested in the number of observations for each district and have therefore created a variable that counts each observation by district and inserts it into a new variable:

bysort id: gen investcount=_N if contractsize !=.

I have merged my data on "contractsize" with the db data set so that for observations from indentical areas the identifier is repeated.

I then plot the map using

spmap investcount using "zmb_admcoord", id(_ID) ///
 fcolor(Reds2) ocolor(dkgreen) osize(thin) ///
 line(data("zamcoord_road") by(type) ///
 color(Greens) size(medium ..) ///
 legenda(on)) legend(position(2))

However now my _ID is no longer unique.

Could someone please show me how I fix this?