r - 使用长字符串按列对 R 数据帧进行排序

Question

如何按包含长字符串的列对 R 数据进行排序？以下示例说明了我的问题:

> a = matrix(NA, nrow=4, ncol=3)
> a[,1] = c(1,2,3,4)
> a[,2] = c("gene001_10M","gene002_10M","gene001_50M","gene002_50M")
> colnames(a) = c("value","sortkey","other")
> a = as.data.frame(a)
> a
  value     sortkey other
1     1 gene001_10M  <NA>
2     2 gene002_10M  <NA>
3     3 gene001_50M  <NA>
4     4 gene002_50M  <NA>

当我现在对“a”进行排序时，排序键似乎是从右向左读取的，而“a”保持不变:

> b = a[sort(a$sortkey),]
> b
  value     sortkey other
1     1 gene001_10M  <NA>
2     2 gene002_10M  <NA>
3     3 gene001_50M  <NA>
4     4 gene002_50M  <NA>

然而，我的目标是:

> b
  value     sortkey other
1     1 gene001_10M  <NA>
3     3 gene001_50M  <NA>
2     2 gene002_10M  <NA>
4     4 gene002_50M  <NA>

Answer 1

当你有numbers、alphabets等时，最好使用gtools中的mixedorder，虽然在这里它适用于 order 单独

  a[order(as.character(a$sortkey)),]
  #  value     sortkey other
  #1     1 gene001_10M  <NA>
  #3     3 gene001_50M  <NA>
  #2     2 gene002_10M  <NA>
  #4     4 gene002_50M  <NA>

此外，使用 sort 会得到 values 而不是 index

   sort(as.character(a$sortkey))
   #[1] "gene001_10M" "gene001_50M" "gene002_10M" "gene002_50M"

否则，您必须在 sort

中指定 index.return=TRUE 默认为 FALSE

   sort(as.character(a$sortkey), index.return=TRUE)
   #$x
  #[1] "gene001_10M" "gene001_50M" "gene002_10M" "gene002_50M"

  #$ix
  #[1] 1 3 2 4

然后，使用

   a[sort(as.character(a$sortkey), index.return=TRUE)$ix,]
  #  value     sortkey other
  #1     1 gene001_10M  <NA>
  #3     3 gene001_50M  <NA>
  #2     2 gene002_10M  <NA>
  #4     4 gene002_50M  <NA>

此外，

  library(gtools)
   mixedorder(as.character(a$sortkey))
   #[1] 1 3 2 4