I am running cross validation on dataset and getting

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() 

error at the beginning of second iteration of for loop of kFCVEvaluate. What am I doing wrong?

I looked at other posts about this error, they are about using and/or operators but I don't use any logical operators.

from sklearn.tree import DecisionTreeRegressor
model = DecisionTreeRegressor(random_state = 42, max_depth=5)

def split_dataset(dataset): 
        numFolds=10 
        dataSplit = list()
        dataCopy = list(dataset)
        foldSize = int(len(dataset) / numFolds)
        for _ in range(numFolds):
            fold = list()
            while len(fold) < foldSize:
                index = randrange(len(dataCopy))
                fold.append(dataCopy.pop(index))
            dataSplit.append(fold)
        return dataSplit
    
def kFCVEvaluate(dataset):

    folds = split_dataset(data)
    scores = list()
    for fold in folds:
        trainSet = list(folds)
        trainSet.remove(fold)
        trainSet = sum(trainSet, [])
        testSet = list()
        for row in fold:
            rowCopy = list(row)
            testSet.append(rowCopy)
            
        trainLabels = [row[-1] for row in trainSet]
        trainSet = [train[:-1] for train in trainSet]
        model.fit(trainSet,trainLabels)
        
        actual = [row[-1] for row in testSet]
        testSet = [test[:-1] for test in testSet]
        
        predicted = model.predict(testSet)
        
        accuracy = actual-predicted
        scores.append(accuracy)
        print(scores)
kFCVEvaluate(data)

CodePudding user response：

Testing my remove hypothesis

In [214]: alist = [np.array([1,2,3]), np.ones(3), np.array([4,5])]
In [215]: alist.remove(np.array([1,2,3]))
Traceback (most recent call last):
  File "<ipython-input-215-0b2a68765241>", line 1, in <module>
    alist.remove(np.array([1,2,3]))
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

remove does work if the list contains lists or tuples

In [216]: alist = [[1,2,3], [1,1,1], [4,5]]
In [217]: alist.remove([1,1,1])
In [218]: alist
Out[218]: [[1, 2, 3], [4, 5]]