numpy。在特定索引處加上多維數組

Question

我試圖用一個向量化的高效操作，使用numpy替換像這樣的代碼。

counter = 0 
idxs = [1, 3] 
lists = [[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]] 
for l in lists: 
    for idx in idxs: 
     counter += l[idx] 

Answer 1

只要求和陣列：

idxs = [1, 3] 
lists = [[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]] 
ary = np.array(lists) 
counter = ary[:,idxs].sum()