如何以省时的方式清除向量的一部分? [英] how to clear part of vector in time efficient way?

问题描述

如何以省时的方式获取向量的一部分并用零填充其他部分?

How can I take part of the vector and fill other part with zero in time efficient way ?

我有一个向量；

 A  |  |                               A  | 0 |               
    |  |                                  | 0 |
    |  |                                  | 0 |
    |  | <-------- x         -----------> |   |  <--|
    |  |                                  |   |     |
    |  |                                  |   |     |     data in this region
    |  |                    after         |   |     |      is not changed
    |  |                                  |   |     |     
    |  |                  operation       |   |     |
    |  |                                  |   |     |
    |  |                                  |   |  <--|
    |  | <--------- y        -----------> |   |
    |  |                                  | 0 |
    |  |                                  | 0 |
    |  |                                  | 0 |

推荐答案

u = 1:10;
v = [1:3, 8:10];

u(v) = 0;

将前3个元素和后3个元素设置为零.为了使其与您对问题的表述方式更加相似:

Will set the first and last 3 elements to zero. To make it more similar to how you phrased the question:

x = 3;
y = 8;
u = 2:2:20;
v = x:y;
w = 1:length(u);

u(setdiff(w, v)) = 0;

尽管您可能更愿意这样做:

Although you would probably prefer to just do:

u(1:x-1) = 0;
u(y+1:end) = 0;

(仅当您想要包含范围时，才+/- 1.)

(The +/-1 is only if you want inclusive range.)

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