Mean of classified data

2 次查看（过去 30 天）
Juanjo Gomez
Juanjo Gomez 2017-5-2
回答： Mann Baidi 2023-12-7
I have a matrix X where each row represents an observation. For example:
X =
1 3
2 5
5 7
and a vector column classes that represents, for each observation in X, which class it belongs to, for example
classes=
1
2
1
That means observation (1,3) and (5,7) are classified as 1 and observation (2,5) is classified as 2.
I'm looking for a efficiently method to calculate the mean of each class, so in this example, I get (3,5) mean for class 1 and (2,5) mean for class 2.

请先登录，再回答此问题。

回答（1 个）

Mann Baidi
Mann Baidi 2023-12-7
Ran in:
Hi Juanjo,
I understand you would like to perform “mean” operations on a classified 2D array.
For this you can use the “accumarray” function in MATLAB to perform arithmetic operations on classified arrays.
You can resolve your query using “accumarray” as follows:
X=[1 3;2 5; 5 7;10 15;64 67];
classes=[1 3 1 2 2]';
res=[accumarray(classes,X(:,1),[],@mean) accumarray(classes,X(:,2),[],@mean)]
res = 3×2
3 5 37 41 2 5
You can refer to the “accumarray” documentation using the following link.
https://www.mathworks.com/help/matlab/ref/accumarray.html
Hope this will help!

类别

在 Help Center 和 File Exchange 中查找有关 Classification 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by