Using a logic mask for selective data operations

53 次查看（过去 30 天）
Wah On Ho
Wah On Ho 2019-12-18
评论： Star Strider 2019-12-18
Hi All. I'm trying to use a logic mask to select data in a numerical matrix, rather than simply looping through each cell, and perform some mathematical operation, and then the inverse maks to perform a different operation. For example...
data = [-2, -4, 1, 3, 4, -6; -0.5, 2.4, 5, 9.8, 3, -11.2; 4, 3, -2, -1.5, 7, 10; 3, 4, -2.4, -3.3, -8, 10];
logicmaskneg = data < 0;
logicmaskpos = data > 0;
dataneg = data(logicmaskneg);
datapos = data(logicmaskpos);
So logicmaskneg and logicmaskpos keep the same matrix structure as data. But dataneg and datapos collapses the data matrix into one column. How do I apply the logic masks such that I can keep dataneg and datapos in the matrix organisation as data so I can continue to perform further calculations preserving the original column and row organisation?
Maybe I'm going about this the wrong way. My aim is to perform one operation on only the negative numbers and a different calculation on the positive numbers while preserving the data layout.
Any help and advice is much appreciated.
Thanks.

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2019-12-18
The ‘logicmaskneg’ and ‘logicmaskpos’ matrices become numeric matrices when used in any calculation.
See if this does whatt you want:
data = [-2, -4, 1, 3, 4, -6; -0.5, 2.4, 5, 9.8, 3, -11.2; 4, 3, -2, -1.5, 7, 10; 3, 4, -2.4, -3.3, -8, 10];
logicmaskneg = data < 0;
logicmaskpos = data > 0;
dataneg = data(logicmaskneg);
datapos = data(logicmaskpos);
producing:
dataneg =
-2 -4 0 0 0 -6
-0.5 0 0 0 0 -11.2
0 0 -2 -1.5 0 0
0 0 -2.4 -3.3 -8 0
datapos =
0 0 1 3 4 0
0 2.4 5 9.8 3 0
4 3 0 0 7 10
3 4 0 0 0 10
  8 个评论
显示 6更早的评论
Wah On Ho
Wah On Ho 2019-12-18
That's exactly what I'm after! I agree, Matlab does make these calculations straightforward once you know. Thank you so much.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Data Type Identification 的更多信息

标签

产品


版本

R2019a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by