I'm working on ArcMap 10. I have a layer of points which I categorized based on a field that we can call "Name". Thus, as you can see in the picture below, the layer is now composed of 24 colors, each of which for points with the same value of "Name". I want to show the labels for this field, but instead of having a label for each point (which as you can assume wouldn't be appropriate given the amount of features) I would have a label for each group of points with the same color (same "Name" value), maybe in the barycenter of the points or linked to the barycenter by an arrow. Is there a way to accomplish this?
You can do this using the Mean Center tool in the Spatial Statistics toolbox, it will compute the average X and Y coordinates for a set of points that you specify and generate an output point. You can specify groups of points in your source data for which individual centers will be computed using the Case Field in the tool, so you would use "Name" as your Case Field to find the center points for each unique Name value.
There's also the Median Center tool, which should generate a similar output but that one works by finding the output location that will result in the shortest distance between each input point and the output point.
You may want to try both tools and see which output looks more like what you're after. Once you've decided, just use those output points as your label points.
I am not sure if this is the best way to do it. But you could create polygons around the points, either draw them or use something like bounding container. Then calculate the centroid of the polygon. Then create the labels for the polygon feature and turn the labels on. Symbolize the poly feature with no color and no outline so only the label appears. You can use leaders to point to the centroid of the poly.
Alternatively you could copy the point feature class (so you have two loaded in the TOC) and use a definition query to select only 1 point for each color (maybe a sql command on FID or Object_ID) Then label the single point features in that FC.
Also just a thought but why not can the labels entirely and use the legend to denote what each color represents?
If you use Maplex labeling, you can check the remove duplicates box, under the label density tab, in placement properties. This will label each classification in your feature once and only once.