Type object 'AllPairs' has no attribute 'params'

Question

When I try QSVM over Iris data, it needs multiclass extension, but when I provide it, a following error is returned:

AttributeError                            Traceback (most recent call last)
<ipython-input-18-86cd4e7dd846> in <module>
      2 
      3 feature_map = ZZFeatureMap(feature_dimension=feature_dim, reps=2, entanglement='linear')
----> 4 qsvm = QSVM(feature_map, training_input, test_input, multiclass_extension=AllPairs)

d:\anaconda\envs\ai\lib\site-packages\qiskit\aqua\algorithms\classifiers\qsvm\qsvm.py in __init__(self, feature_map, training_dataset, test_dataset, datapoints, multiclass_extension, quantum_instance)
    148         else:
    149             multiclass_extension.set_estimator(_QSVM_Estimator, [feature_map])
--> 150             qsvm_instance = _QSVM_Multiclass(self, multiclass_extension)
    151 
    152         self.instance = qsvm_instance

d:\anaconda\envs\ai\lib\site-packages\qiskit\aqua\algorithms\classifiers\qsvm\_qsvm_multiclass.py in __init__(self, qalgo, multiclass_classifier)
     37         super().__init__(qalgo)
     38         self.multiclass_classifier = multiclass_classifier
---> 39         self.multiclass_classifier.params.append(qalgo)
     40 
     41     def train(self, data, labels):

AttributeError: type object 'AllPairs' has no attribute 'params'

The code is :

seed = 10598

feature_map = ZZFeatureMap(feature_dimension=feature_dim, reps=2, entanglement='linear')
qsvm = QSVM(feature_map, training_input, test_input, multiclass_extension=AllPairs)
```

Answer 1

The multiclass code was refactored a little some while ago. Here is a tutorial showing the use of these classifiers with QSVM that works with how things are now that should help https://github.com/qiskit-community/qiskit-community-tutorials/blob/master/machine_learning/qsvm_multiclass.ipynb

You will see you now pass an instance of the multiclass in and no longer have that other setup around the multiclass extension and the algorithm.