Setting precision for decimal values when labeling layer with PyQGIS

Question

I am currently working on a project in which I need to turn on the "RESULT_PRE" field label so this is the code but the field holds decimal values and I want to give a precision of 3 digits. How can I do that?

from qgis.core import QgsProject
from qgis.core import *
from qgis.utils import iface
from qgis.core import QgsEditorWidgetSetup,QgsField
from qgis.core import QgsPalLayerSettings, QgsTextFormat


# Get the active layer
layer = iface.activeLayer()
layer.setLabelsEnabled(True)
label_Settings = QgsPalLayerSettings()
label_Settings.fieldName = "RESULT_PRE"

# Optional: Set label formatting (e.g., font, size, color)
text_format = QgsTextFormat()
text_format.setFont(QFont("Arial", 12))  # Set font and size
label_Settings.setFormat(text_format)

# Enable labelling for the layer
layer.setLabeling(QgsVectorLayerSimpleLabeling(label_Settings))

# Refresh the layer to apply the changes
layer.triggerRepaint()

Answer 1

You are almost there, there are only two additional settings parameters that you were missing label_Settings.formatNumbers = True and label_Settings.decimals = 3 of the QgsPalLayerSettings class.

So, in the end, your code may look like this:

from qgis.core import QgsProject
from qgis.core import *
from qgis.utils import iface
from qgis.core import QgsEditorWidgetSetup,QgsField
from qgis.core import QgsPalLayerSettings, QgsTextFormat
    

# Get the active layer
layer = iface.activeLayer()
layer.setLabelsEnabled(True)
label_Settings = QgsPalLayerSettings()
label_Settings.fieldName = "RESULT_PRE"
label_Settings.formatNumbers = True # active to fix number of decimal places
label_Settings.decimals = 3 # set up required precision

# Optional: Set label formatting (e.g., font, size, color)
text_format = QgsTextFormat()
text_format.setFont(QFont("Arial", 12))  # Set font and size
label_Settings.setFormat(text_format)

# Enable labeling for the layer
layer.setLabeling(QgsVectorLayerSimpleLabeling(label_Settings))

# Refresh the layer to apply changes
layer.triggerRepaint()

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References:

• Setting number of Decimals for QgsPalLayerSettings object