如何在Matlab中将具有相同值的数字相加 [英] How to add up numbers with same value in matlab

问题描述

所以，如果我有一个数字数组:

So if i have an number array:

a     b
1     2.5 
1     1.2 
3     2.5
4     0.4
6     3
3     1.2

我想对a列中的数字求和，第2列中b的值相同:

i want to sum up numbers in column a with same value of of b in column 2, like this:

a   b
4   2.5 
4   1.2 
4   0.4
6   3

因此您可以看到1和3相加并变成4，因为它们具有相同的b值，即2和其余的数字，所以我将如何做呢?谢谢 (PS:我的真实数据是整数和十进制数字的组合，谢谢)

so as you can see 1 and 3 add up and became 4, because they have the same value of b which is 2 and also to the rest of the numbers, so how i will do that? thanks (PS: my real data is combination of integers and decimal no. thanks)

推荐答案

假定A为输入数组，您可以在此处使用两种方法.

Assuming A to be the input array, you have two approaches to play with here.

方法1

accumarray 和

---

方法2

使用 bsxfun -

[unqcol2,~,idx] = unique(A(:,2),'stable')
[sum(bsxfun(@times,bsxfun(@eq,idx,1:max(idx)),A(:,1)),1).' unqcol2 ]

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