I'm trying to set the color of a vectorlayer feature depending on the feature attributes with PyQGIS. How do you acces the attributes of a vectorlayer feature?
Right click on the layer in the table of contents > properties > style tab > there you have options to style as a single symbol, using categories, using graduated colours, and rules.
You then have the option to choose the field containing the values to be displayed.
See the QGIS manual for more information: http://docs.qgis.org/user_guide/html/en/