Classification

#You can use any of these classification method classes:
#QgsClassificationQuantile()
#QgsClassificationEqualInterval()
#QgsClassificationJenks()
#QgsClassificationPrettyBreaks()
#QgsClassificationLogarithmic()
#QgsClassificationStandardDeviation()

Intervalles égaux

[code]# Set layer name and desired paremeters
layer_name = 'simple_countries'
ramp_name = 'Spectral'
value_field = 'population'
num_classes = 5
classification_method = QgsClassificationEqualInterval()

layer = QgsProject().instance().mapLayersByName(layer_name)[0]

# change format settings as necessary
format = QgsRendererRangeLabelFormat()
format.setFormat("%1 - %2")
format.setPrecision(2)
# format.setTrimTrailingZeroes(True)

default_style = QgsStyle().defaultStyle()
color_ramp = default_style.colorRamp(ramp_name)

renderer = QgsGraduatedSymbolRenderer()
renderer.setClassAttribute(value_field)
renderer.setClassificationMethod(classification_method)
renderer.setLabelFormat(format)
renderer.updateClasses(layer, num_classes)
renderer.updateColorRamp(color_ramp)

layer.setRenderer(renderer)
layer.triggerRepaint()[/code]