diagramlabelingqgis
I'm working with QGIS 2.14.3, using the diagrams function for vector layers. Is it possible to label each single diagram sector with an attribute / calculated percentage? In the layer properties tab / labels I only see an option to label the whole feature. In the diagrams menu, I can't find any labelling option.
It would be very nice to label for example every single pillar in this diagram with an attribute / calculated percentage. The displayed label is the label of the whole feature.
You can publicly access many of the 'advanced' (or PAL) labeling engine functions via several classes, though the settings classes do not have sip (Python) bindings yet:
This is the main PAL engine interface that is really part of QgsMapRenderer, so you will want to gain access to it with the following in QGIS's Python console:
iface = qgis.utils.iface
mc = iface.mapCanvas()
mr = mc.mapRenderer()
le = mr.labelingEngine()
You will generally not need to work with the engine via Python. One aspect of accessing the engine directly that might be useful: gain direct access to the labels that have already be rendered. This is how the PAL label manipulation tools in the toolbar work (from master branch: Pin/Unpin, Show/Hide, Move, Rotate, Change):
le.labelsAtPosition(QgsPoint) # returns a label of class QgsLabelPosition
le.labelsWithinRect(QgsRectangle) # returns list of labels
# e.g. le.labelsWithinRect(mc.extent()) would return all visible labels drawn to canvas
see also: QgsLabelPosition
This is where you can set temporary engine-specific options like search method, show candidates, etc. as you can in the Engine settings dialog. There is currently no Python binding for this class.
Having a sip file created (Python binding) for this class, and the following, is the feature request you will want to submit, as per @lynxlynxlynx's suggestion.
This is where you can access, manipulate and write PAL settings for a given vector layer (which I think is what you are looking to do). Unfortunately, there is currently no Python binding for this class, which is defined in the QgsPalLabeling file, and I don't think there is a means of accessing it via another bound class.
Once a binding is in place, you will probably be able to access PAL layer settings like:
palyr = QgsPalLayerSettings()
palyr.readFromLayer(iface.activeLayer()) # assuming active layer is of vector type
if not pallyr.labelPerPart: # access "Label every part of a multi-part feature"
pallyr.labelPerPart = True
palyr.writeToLayer(iface.activeLayer())
# you have just adjusted settings like via the GUI, now redraw the canvas
mc.refresh()
Check the the QgsPalLabeling class's header and source file comments for info on defaults for QgsPalLayerSettings options.
You don't need data in the attribute table to apply a label. You can apply an identical text label to every feature in a layer by simply entering text surrounded by single quotation marks.
If you want each feature to have a unique label, that's where you would need information in the attribute table. Add a field to the attribute table, give each feature a value in that field, then use that field in the Layer properties > Labels > Label with... Here's a quick photo guide to adding a field to the attribute table:
These are pretty basic tasks in QGIS. If you take the time to work through these QGIS tutorials, you'll have a much easier time using this program.
Best Answer
In QGIS you can not add labels to diagrams.
table attribute
style 'symbol SVG'
assembly view of
other diagrams