在Matlab中使用accumarray求和数据
我有这样一个矩阵:在Matlab中使用accumarray求和数据,matlab,matrix,accumarray,Matlab,Matrix,Accumarray,我有这样一个矩阵: >>D=[1,0,10;3,1,12;3,1,12.5;6,1,6;6,2,11.1;] D = 1.0000 0 10.0000 3.0000 1.0000 12.0000 3.0000 1.0000 12.5000 6.0000 1.0000 6.0000 6.0000 2.0000 11.1000 如果第一列数据相同,我想得到第二列数据的总和。例如,我想要: E= 1.0000
>>D=[1,0,10;3,1,12;3,1,12.5;6,1,6;6,2,11.1;]
D =
1.0000 0 10.0000
3.0000 1.0000 12.0000
3.0000 1.0000 12.5000
6.0000 1.0000 6.0000
6.0000 2.0000 11.1000
如果第一列数据相同,我想得到第二列数据的总和。例如,我想要:
E=
1.0000 0
3.0000 2.0000
6.0000 3.0000
所以我试过了
b = accumarray(D(:,1),D(:,2),[],[],[],true);
[i,~,v] = find(b);
E = [i,v]
但它不起作用。我该怎么办?以这种方式结合使用
unique
和accumarray
-
[unique_ids,~,idmatch_indx] = unique(D(:,1));
%// unique_ids would have the unique numbers from first column and only
%// used to get the first column of final output, E.
%// idmatch_indx are tags put on each element corresponding to each unique_ids
%// based on the uniqueness
%// Accumulate and perform summation of elements from second column of D using
%// subscripts from idmatch_indx
E = [unique_ids accumarray(idmatch_indx,D(:,2))]
使用accumarray
时,通常需要输入要在累积元素上使用的函数,但是@sum
是默认函数句柄,在这种情况下,您可以忽略它