fuzzy system python assertion error during input

Question

I have built a fuzzy control system that takes three inputs (x,y,z) that accept (poor, average, or good) values and returns one output (w) with (low, average, or high) value. unfortunately, when I test the system I get an assertion error without any additional information. the code used to build the system is shown below.

import numpy as np
import skfuzzy as fuzz
from skfuzzy import control as ctrl
import matplotlib.pyplot as plt
from matplotlib import rc
x=ctrl.Antecedent(np.arange(0,1,0.001), 'x')
y=ctrl.Antecedent(np.arange(0,1,0.001), 'y')
z=ctrl.Antecedent(np.arange(0,1,0.001), 'y')
w=ctrl.Consequent(np.arange(0,1,0.1),'w')
x.automf(3)
y.automf(5)
z.automf(7)
w['low'] = fuzz.trimf(w.universe, [0, 0, 0.3])
w['average'] = fuzz.trimf(w.universe, [0.25, 0.5, 0.75])
w['high'] = fuzz.trimf(w.universe, [0.7, 1, 1])
rule1 = ctrl.Rule(x['poor'] & y['poor'] & z['poor'], w['low'])
rule2 = ctrl.Rule(x['poor'] & y['poor'] & z['good'], w['low'])
rule3 = ctrl.Rule(x['poor'] & y['good'] & z['poor'], w['high'])
rule4 = ctrl.Rule(x['poor'] & y['good'] & z['good'], w['average'])
rule5 = ctrl.Rule(x['good'] & y['poor'] & z['poor'], w['low'])
rule6 = ctrl.Rule(x['good'] & y['poor'] & z['good'], w['low'])
rule7 = ctrl.Rule(x['good'] & y['good'] & z['poor'], w['average'])
rule8 = ctrl.Rule(x['good'] & y['good'] & z['good'], w['low'])
w_ctrl = ctrl.ControlSystem([rule1, rule2, rule3, rule4, rule5, rule6, rule7, rule8])
wResults= ctrl.ControlSystemSimulation(w_ctrl)
wResults.input['x'] = 0.03
wResults.input['y'] = 0.7
wResults.input['z'] = 0.01
wResults.compute() 

and the error I get is:

AssertionError                            Traceback (most recent call last)
<ipython-input-162-4519156d7582> in <module>()
     25 wResults= ctrl.ControlSystemSimulation(w_ctrl)
     26 wResults.input['x'] = 0.03
---> 27 wResults.input['y'] = 0.7
     28 wResults.input['z'] = 0.01
     29 wResults.compute()

C:\Users\user01\Anaconda3\lib\site-packages\skfuzzy\control\controlsystem.py in __setitem__(self, key, value)
    129         if len(matches) == 0:
    130             raise ValueError("Unexpected input: " + key)
--> 131         assert len(matches) == 1
    132         var = matches[0]
    133 

AssertionError: 

I wonder if anybody have an idea where this code went wrong.

Answer 1

First problem is a typo,

z = ctrl.Antecedent(np.arange(0,1,0.001), 'y')    # should be 'z'!

Now the code, when run, returns

ValueError: Crisp output cannot be calculated, likely because the system is too sparse.
 Check to make sure this set of input values will activate at least one connected Term
 in each Antecedent via the current set of Rules.

... because

wResults.input['y'] = 0.7     # classifies as "decent",
                              # and you haven't given any relevant rules