X = sparse.rand(100, 10000)
xt = np.random.random((100, 1))
xt = xt.astype('object')
print('X:', X.shape, X.dtype)
print('xt:', xt.shape, xt.dtype)
print('Stacked shape:', sparse.hstack((X, xt)).shape)
Numpy hstack - "ValueError: all the input arrays must have same number of dimensions" - but they do