Modify layer's renderer with pyQGIS (QgsGraduatedSymbolRenderer)

Question

I want to modify the color ramp of my layer in pyQGIS like I would do it in the layer properties :

I identified QgsGraduatedSymbolRenderer().updateColorRamp(ramp=color_ramp) as the function to update it, but I can't link it to my maplayer. How can I access the renderer of a layer ?

Answer 1

Thanks to Matt, I got the working code :

renderer = mylayer.renderer()
if isinstance(renderer, QgsGraduatedSymbolRenderer):
    if color_ramp is None:
        default_style = QgsStyle().defaultStyle()
        color_ramp = default_style.colorRamp('Spectral')  # Spectral color ramp
        color_ramp.invert()
    renderer.updateColorRamp(ramp=color_ramp)

    if myfield is not None:
        renderer.setClassAttribute(myfield)
        mylayer.setRenderer(renderer)
        mylayer.triggerRepaint()