计算 R 中矩阵中每列因子的出现次数

Question

我有一个大矩阵（10000 列和 600 行），下面显示了一个示例，其中包含核苷酸，但也包含 NA。我想计算每列每个核苷酸（因子）的出现次数，但忽略 NA。输出应该在一个列表中。

`r1 <- c("a","c","a","a","t","c")
 r2 <- c("a","c","t","t","c","a")
 r3 <- c("a","g","g","c","a","c")
 r4 <- c("a","g","g","g","g","c")
 r5<- c(NA, "g","g","g","t","g")

 n.mat <- rbind(r1,r2,r3,r4,r5)`

输出应该在一个列表中，该列表仅包含每列中每个核苷酸的出现次数。所以每个 List 元素都应该包含一列的数字。

[[1]]
[1] "4"
[[2]]
[2] "2" "3"
[[3]]
[3] "1" "1" "3"
[[4]]
[4] "1" "1" "1" "2"
[[4]]
[4] "2" "1" "1" "1"
[[5]]
[5] "3" "1" "1"

我已经在尝试找到解决方案，但我不知道如何实际计算矩阵中每列的出现次数。我的代码是：

alleles_nmat <- apply(n.mat, 2, function(x) unique(x[!is.na(x)]))

我希望有人可以帮助我。

Answer 1

喜欢这样吗？

apply(n.mat, 2, table)
[[1]]

 a NA 
 4  1 

[[2]]

c g  
2 3 

[[3]]

a g t 
1 3 1 

[[4]]

a c g t 
1 1 2 1 

[[5]]

a c g t 
1 1 1 2 

[[6]]

a c g 
1 3 1