在R中使用数据框填充矩阵 [英] Filling a matrix using a dataframe in R

问题描述

我有一个空矩阵 m ：

m <- matrix(0, nrow = 4, ncol = 2, byrow = TRUE,
            dimnames = list(c("sp1", "sp2", "sp3", "sp4"),
                            c("x", "y")))

还需要使用数据框填充矩阵d

And need to fill the matrix using the data frame d

d <- data.frame(site = c("x", "y", "u", "v"), 
                species = c("sp1", "sp1", "sp1", "sp1"), 
                freq = c(0.2, 0.3, 0.5, 0.1))

所以如果 rowname（m）等于 d [，species] 和 m [，x] 等于 d [ site] then d [，freq] 输入到矩阵中的正确位置，即返回：

so that if rowname(m) is equal to d[, "species"] and m[, "x"] is equal to the d[, "site"] then d[, "freq"] in entered in the correct place in matrix m i.e. returning:

m <- matrix(c(0.2, 0, 0, 0, 0, 0, 0, 0), nrow = 4, ncol = 2, byrow = TRUE, 
            dimnames = list(c("sp1", "sp2", "sp3", "sp4"),
                            c("x", "y")))

我尝试过：

m[d[, c("species", "x")]] <- d[, "freq"]

我怀疑我没有正确地进行数据帧索引？有任何想法吗？谢谢。

I suspect I am not doing the data frame indexing properly? Any ideas? Thanks.

推荐答案

这可能不是最好的方法，但这是正常工作：

That is probably not the best way to do it but this is working:

for(i in 1:nrow(d)){m[rownames(m)==d[i,2],colnames(m)==d[i,1]] <- d[i,3]}

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