Creating points on a map

[Veronique Meertens]

Hi everybody,

I am having some trouble getting my map out of stata.
I already obtained the right datasets. The trouble starts when I try to add points.
My simplified code looks like this:

- use "NL-attr.dta"
- spmap using "NL-coord.dta", id(NLid) fcolor(eggshell) ocolor(black)

I get a nice map of the Netherlands, so now I try to add some points to the map:

- spmap using "NL-coord.dta", id(NLid) fcolor(eggshell) ocolor(black) point(data("Pointscoord.dta") xcoord(xcoord) ycoord(ycoord) fcolor(red))

Now I only see the points, but the map of the Netherlands is gone.
Does anyone know what I am doing wrong?
I have added to two maps, maybe it helps.

Thanks and kind regards

[Marcos Almeida]

Hi Veronique,

I recommend you create the centroids beforehand. For this, you can use the SSC shp2dta with the option genc(c). Then you may select x_c and y_c as xcoord and ycoord, respectively, under - spmap - commands.

Hopefully that works for you!

Best,

Marcos

[Chinh Nguyen]

Dear Veronique,

I think you was confuse between Long and Lat when you confirm xcoord and ycoord, like me!

Best.

[Jorrit Gosens]

Marcos: I think these are probably city locations, and if so, that approach won't work here.
I agree with Chinh, or a least I think he makes he same point: the most likely explanation is that your NL-coord.dta uses a different coordinate system than your Pointscoord.dta.
With maps it is quite usual to think in terms of latitude and longitude as they are defined on a global map, but quite a few map databases use just coordinates from an origin being the bottom left corner or the area to be drawn on, rather than coordinates from 0 latitude and 0 longitude on a global map.

Oh, and a possible solution, assuming that you do just want to draw points using lat/lon, is to find a shapefile that uses such a system for drawing a map of Holland.