匹配和替换 for 循环

Question

for 循环有问题。

我正在尝试从每个途径（途径矩阵）中获取元素 a b c d 并将它们与表达数据（表达矩阵）进行匹配，并将它们放入一个看起来类似于途径矩阵但现在包含来自表达矩阵的元素的新矩阵中。

我正在努力实现这个最终的矩阵结果。

a <- c("pathway","1","4","7","pathway-2","1","e","g","pathway-3","4","g","h")
pathway<-matrix(a,3,4, byrow=T)

代码将比我希望的措辞更容易理解。

a <- c("pathway","b","c","d","pathway-2","b","e","g","pathway-3","c","g","h")
pathway<-matrix(a,3,4, byrow=T)

b <- c("b",1,"c",4,"d",7)
expression<-matrix(b,3,2, byrow=T)

new<-matrix("a",3,4)
new[1:3,1]<-pathway[,1]

for (x in 1:nrow(expression)){
  for (y in 1:ncol(pathway)){
    if(expression[x,1]==pathway[x,y]){
      new[x,y]<-expression[x,2]
    }
  }
}

Answer 1

这是一种方法。我们将pathway[,-1] 的每一列与expression[,1] 矩阵相匹配，并将生成的矩阵用作expression[,2] 中值的索引。未找到的返回NA，因此我们对它们进行索引并从原始矩阵中替换它们。然后像往常一样cbind 得到想要的矩阵。

new_m <- apply(pathway[, -1], 2, function(i) expression[,2][match(i, expression[,1])])
new_m[which(is.na(new_m))] <- pathway[,-1][which(is.na(new_m))]
cbind(pathway[,1], new_m)
#     [,1]        [,2] [,3] [,4]
#[1,] "pathway"   "1"  "4"  "7" 
#[2,] "pathway-2" "1"  "e"  "g" 
#[3,] "pathway-3" "4"  "g"  "h"