如何按用户定义的数据框排序（例如非字母顺序）

Question

给定数据框dna

> dna
chrom   start
chr2    39482
chr1    203918
chr1    198282
chrX    7839028
chr17   3874

以下代码按字母升序排列dna {1}}按升序排列$chrom按字母升序排序：

$start

但是，我希望能够按如下方式排序> dna <- dna[with(dna, order(chrom, start)), ] > dna chrom start chr1 198282 chr1 203918 chr17 3874 chr2 39482 chrX 7839028 （为了我的例子而简化）：

$chrom

我不允许重命名内容，例如chrom_order <- c("chr1","chr2", "chr17", "chrX") 到chr1。

Answer 1

您需要在levels中指定factor，然后使用order编制索引：

zz <- "chrom   start
chr2    39482
chr1    203918
chr1    198282
chrX    7839028
chr17   3874"
Data <- read.table(text=zz, header = TRUE)

library(Hmisc)
library(gdata)

Data$chrom  <- reorder.factor(Data$chrom , levels = c("chr1","chr2", "chr17", "chrX"))

Data[order(Data$chrom), ]
  chrom   start
2  chr1  203918
3  chr1  198282
1  chr2   39482
5 chr17    3874
4  chrX 7839028  

或者你可以使用它：

> Data$chrom  <- factor(chrom , levels = c("chr1","chr2", "chr17", "chrX"))
> Data[order(Data$chrom), ]
  chrom   start
2  chr1  203918
3  chr1  198282
1  chr2   39482
5 chr17    3874
4  chrX 7839028

或使用此：

> Data$chrom <- reorder(Data$chrom, new.order=c("chr1","chr2", "chr17", "chrX"))
> Data[order(Data$chrom), ]

Answer 2

试试这个：

dna <- structure(list(chrom = structure(c(2L, 1L, 1L, 4L, 3L), .Label = c("chr1", 
"chr2", "chr17", "chrX"), class = c("ordered", "factor")), start = c(39482L, 
203918L, 198282L, 7839028L, 3874L)), .Names = c("chrom", "start"
), row.names = c(NA, -5L), class = "data.frame")

chrom_order <- c("chr1","chr2", "chr17", "chrX")

# Make chrom column ordered. Second term defines the order
dna$chrom <- ordered(dna$chrom, chrom_order)
dna[with(dna, order(chrom, start)),]

 chrom   start
3  chr1  198282
2  chr1  203918
1  chr2   39482
5 chr17    3874
4  chrX 7839028