Function string_kernel

sklearn/svm/tests/test_svm.py:1400–1410

(X1, X2)

    y = np.array([1, 1, 2, 2, 1])

    def string_kernel(X1, X2):
        assert isinstance(X1[0], str)
        n_samples1 = _num_samples(X1)
        n_samples2 = _num_samples(X2)
        K = np.zeros((n_samples1, n_samples2))
        for ii in range(n_samples1):
            for jj in range(ii, n_samples2):
                K[ii, jj] = X1[ii].count("A") * X2[jj].count("A")
                K[ii, jj] += X1[ii].count("B") * X2[jj].count("B")
                K[jj, ii] = K[ii, jj]
        return K

    K = string_kernel(data, data)
    assert_array_equal(np.dot(X, X.T), K)