Question

假设我有一个numpy数组x = np.array([0, 1, 2])，python中是否有内置函数，以便将元素转换为相应的数组？

e.g。我想将x中的0转换为[1,0,0]，将1转换为[0,1,0]，将2转换为[0,0,1]，预期输出为np.array([[1, 0, 0], [0, 1, 0], [0, 0, 1]])

我试过了x[x == 0] = np.array([1, 0, 0])，但它没有用。

Answer 1

演示：

In [38]: from sklearn.preprocessing import OneHotEncoder

In [39]: ohe = OneHotEncoder()

# modern versions of SKLearn methods don't like 1D arrays
# they expect 2D arrays, so let's make it happy ;-)    
In [40]: res = ohe.fit_transform(x[:, None])

In [41]: res.A
Out[41]:
array([[ 1.,  0.,  0.],
       [ 0.,  1.,  0.],
       [ 0.,  0.,  1.]])

In [42]: res
Out[42]:
<3x3 sparse matrix of type '<class 'numpy.float64'>'
        with 3 stored elements in Compressed Sparse Row format>

用numpy数组替换1d numpy数组中的元素

1 个答案: