How to find polygons centroids? [duplicate]

Question

Possible Duplicate:
Get list of coordinates for points in a layer?

Sorry for another basic question - my map is almost done but now my boss wants me to enter new outbreaks (that we don't have coordinates for) into a map that has animal population data for several provinces (one shapefile for each country).

At this point all I have for these newer outbreaks is the province that the outbreak was in - my boss has said that I can input the coordinates (roughly) for each outbreak by finding the centroid. I've used ftools for this, I've been importing data for outbreaks from excel files (using a delimited text layer) - for the outbreaks without coordinates (for which I only have data telling me what province the outbreak was in) I presume I'm going to have to make an Excel/DBF file with these coordinates. My boss says that I can get these coordinates by finding the centroids.

I've tried using "Polygon Centroids" via the ftools plugin, and have a new shapefile with points on where I presume the center of each province is.

What I'd ideally like is a list (such as in the attribute table) next to each province (which are listen in the attribute table of the shapefile I'm working with) with the coordinates for each centroid. Is there any way to get this done? The only other thing I can imagine is writing down the coordinates of each centroid of each province manually.

Answer 1

You can add coordinates to your shapefile with the polygon centroids by "Vector > Geometry Tools > Export/Add Geometry Columns".

Then go to "layer properties > tab Join" to join that layer to your original province layer. (Make sure you have a common field in both layers to join with.) After the join, save your province layer as a new vector layer to establish the join.