Singleton array array(<function train at 0x7f3a311320d0>, dtype=object) cannot be considered a valid collection

Question

Not sure how to fix . Any help much appreciate. I saw thi Vectorization: Not a valid collection but not sure if i understood this

train = df1.iloc[:,[4,6]]
target =df1.iloc[:,[0]]

def train(classifier, X, y):
    X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.25, random_state=33)
    classifier.fit(X_train, y_train)
    print ("Accuracy: %s" % classifier.score(X_test, y_test))
    return classifier

trial1 = Pipeline([
         ('vectorizer', TfidfVectorizer()),
         ('classifier', MultinomialNB()),])

train(trial1, train, target)

error below :

    ----> 6 train(trial1, train, target)

    <ipython-input-140-ac0e8d32795e> in train(classifier, X, y)
          1 def train(classifier, X, y):
    ----> 2     X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.25, random_state=33)
          3 
          4     classifier.fit(X_train, y_train)
          5     print ("Accuracy: %s" % classifier.score(X_test, y_test))

    /home/manisha/anaconda3/lib/python3.5/site-packages/sklearn/model_selection/_split.py in train_test_split(*arrays, **options)
       1687         test_size = 0.25
       1688 
    -> 1689     arrays = indexable(*arrays)
       1690 
       1691     if stratify is not None:

    /home/manisha/anaconda3/lib/python3.5/site-packages/sklearn/utils/validation.py in indexable(*iterables)
        204         else:
        205             result.append(np.array(X))
    --> 206     check_consistent_length(*result)
        207     return result
        208 

    /home/manisha/anaconda3/lib/python3.5/site-packages/sklearn/utils/validation.py in check_consistent_length(*arrays)
        175     """
        176 
    --> 177     lengths = [_num_samples(X) for X in arrays if X is not None]
        178     uniques = np.unique(lengths)
        179     if len(uniques) > 1:

    /home/manisha/anaconda3/lib/python3.5/site-packages/sklearn/utils/validation.py in <listcomp>(.0)
        175     """
        176 
    --> 177     lengths = [_num_samples(X) for X in arrays if X is not None]
        178     uniques = np.unique(lengths)
        179     if len(uniques) > 1:

    /home/manisha/anaconda3/lib/python3.5/site-packages/sklearn/utils/validation.py in _num_samples(x)
        124         if len(x.shape) == 0:
        125             raise TypeError("Singleton array %r cannot be considered"
    --> 126                             " a valid collection." % x)
        127         return x.shape[0]
        128     else:

    TypeError: Singleton array array(<function train at 0x7f3a311320d0>, dtype=object) cannot be considered a valid collection.

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Not sure how to fix . Any help much appreciate. I saw thi Vectorization: Not a valid collection but not sure if i understood this

Answer 1

I got the same error in another context (sklearn train_test_split) and the reason was simply that I had passed a positional argument as keyword argument which led to misinterpretation in the called function.