我想根据矩阵的行名分组求和,举个例子如下,行名同是 A 的合并,同是 B 的合并,以此类推
tmp <- matrix(data = sample(1:10, 12, replace = T), ncol = 2)
rownames(tmp) <- c("A", "B", "B", "B", "C", "A")
tmp
[,1] [,2]
A 8 6
B 6 8
B 7 5
B 5 8
C 1 7
A 3 3
<sup>Created on 2019-06-09 by the reprex package (v0.3.0)</sup>
我希望的输出是
tmp
[,1] [,2]
A 11 9
B 18 21
C 1 7