resultats = {'Dupont': {
                           'DS1': [15.5, 4],
                           'DM1': [14.5, 1],
                           'DS2': [13, 4],
                           'PROJET1': [16, 3],
                           'DS3': [14, 4]
                       },
             'Durand': {
                           'DS1': [6 , 4],
                           'DM1': [14.5, 1],
                           'DS2': [8, 4],
                           'PROJET1': [9, 3],
                           'IE1': [7, 2],
                           'DS3': [8, 4],
                           'DS4':[15, 4]
                       }
            }

def moyenne(nom, dico_result):
    if nom in ...:
        notes = dico_result[nom]
        total_points = ...
        total_coefficients = ...
        for ...  in notes.values():
            note, coefficient = valeurs
            total_points = total_points + ... * coefficient
            total_coefficients = ... + coefficient
        return round( ... / total_coefficients, 1 )
    else:
        return -1