制作一個 numpy 零數組，其中每行有 8 個零，對應於輸出的索引更改為 1

Question

我想創建一個 numpy 零數組：

Y_numpy = [[0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,0,0],
...]

我有：

Y = [1,2,7,8,3,4,6,7,8,8,8,8,8,4,4,4,6,3,2,3,4,5,6,7,...]

我的目標是將 Y_numpy 中索引處的值更改為“1”，這與每個 Y 的值相同。

例如：

Y[0] = 1 => Y_numpy[0] = [1,0,0,0,0,0,0,0]
Y[1] = 2 => Y_numpy[1] = [0,1,0,0,0,0,0,0]
Y[2] = 7 => Y_numpy[2] = [0,0,0,0,0,0,1,0]
Y[3] = 8 => Y_numpy[3] = [0,0,0,0,0,0,0,1]
Y[4] = 3 => Y_numpy[4] = [0,0,1,0,0,0,0,0]
Y[5] = 4 => Y_numpy[5] = [0,0,0,1,0,0,0,0]
...

如果您需要任何其他信息或更多解釋，請告訴我。

Answer 1

干得好：

Y = [1,2,7,8,3,4,6,7,8,8,8,8,8]
Y_numpy = np.array(Y)[:,None] == np.arange(1,9)

輸出：

array([[ True, False, False, False, False, False, False, False],
       [False,  True, False, False, False, False, False, False],
       [False, False, False, False, False, False,  True, False],
       [False, False, False, False, False, False, False,  True],
       [False, False,  True, False, False, False, False, False],
       [False, False, False,  True, False, False, False, False],
       [False, False, False, False, False,  True, False, False],
       [False, False, False, False, False, False,  True, False],
       [False, False, False, False, False, False, False,  True],
       [False, False, False, False, False, False, False,  True],
       [False, False, False, False, False, False, False,  True],
       [False, False, False, False, False, False, False,  True],
       [False, False, False, False, False, False, False,  True]])

Answer 2

In [179]: Y = [1,2,7,8,3,4,6,7,8,8,8,8,8,4,4,4,6,3,2,3,4,5,6,7]                 
In [180]: len(Y)                                                                
Out[180]: 24
In [181]: Ynum = np.zeros((24,8),int) 

二維數組賦值； 每行一個值：

In [184]: Ynum[np.arange(24),np.array(Y)-1] = 1                                 
In [185]: Ynum[:6,:]                                                            
Out[185]: 
array([[1, 0, 0, 0, 0, 0, 0, 0],
       [0, 1, 0, 0, 0, 0, 0, 0],
       [0, 0, 0, 0, 0, 0, 1, 0],
       [0, 0, 0, 0, 0, 0, 0, 1],
       [0, 0, 1, 0, 0, 0, 0, 0],
       [0, 0, 0, 1, 0, 0, 0, 0]])