how can i avoid the for loop in this case?

1 次查看（过去 30 天）
Dror Aizik
Dror Aizik 2020-5-12
评论： Dror Aizik 2020-5-12
a_matrix=zeros(10,4);
a=[3 6 7 8]';
for i=1:numel(a)
a_matrix(a(i),i)=1;
end
disp(a_matrix)
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 1 0
0 0 0 1
0 0 0 0
0 0 0 0

请先登录，再回答此问题。

采纳的回答

Stephen23
Stephen23 2020-5-12
编辑：Stephen23 2020-5-12
Method one: logical equals:
>> a = [3,6,7,8];
>> V = 1:10;
>> M = double(V(:)==a) % requires MATLAB >= R2016b
M =
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 1 0
0 0 0 1
0 0 0 0
0 0 0 0
For earlier MATLAB versions replace == with bsxfun.
Method two: sub2ind:
>> M = zeros(10,4);
>> X = sub2ind(size(M),a,1:4);
>> M(X) = 1
M =
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 1 0
0 0 0 1
0 0 0 0
0 0 0 0

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息

标签


Translated by