labelingqgis
I am trying to change the font size of the feature labels based on attributes from a field. I can't find an example of how to do this.
I believe I can do this by setting up a data defined expression in the Labels>Text>Size expression but I am not sure how to formulate the actual expression.
I am looking for an example of how this expression would be set up.
Yes! One can definitely set different font sizes for different fields within a single label. Please see this Link: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00s800000027000000.htm
Look at the font attribute. You can set a particular size for the important part of the label and a smaller size for the less important part.
The arcpy.mapping API only provides access to a limited number of layer properties that can be directly modified but all properties found in the Layer Properties dialog box can be modified using the UpdateLayer function. The information is extracted from a source layer and applied to the layer in a map document that needs to be updated. The source_layer can either be a layer (.lyr) file or a layer within a map document. UpdateLayer is a robust function because it can be used in several different ways to produce different results.
You need to create the symbology/labels how you want, and save it to a layer file. Then load that layer file using arcpy.mapping.UpdateLayer().
If multiple people need to run the python add-in, then you need to make the layer file accessible to everyone, such as a public network drive.
I ended up making a custom Update Layer Properties toolbox. It allows you to select a layer in the ArcMap TOC, and then select an input layer file. It then updates the layer with all the properties within the layer file, and re-sources back to the original feature class. It will work with data that's in gdb, mdb, shp, or sde.
Please let me know if you have any questions.
Best Answer
Firstly, go on the
Layer Properties>Labels>Textwindow.Then, edit the expression for the text size (I marked it in the image below):
In the expression field, simply write the name of the field which stores the sizes for the fonts of the labels. In my case, the field was called
font_height, so I wrote (remember to use these" "):Finally, click on the Apply button and this will be the result: