1、問題

> x <- c(1, 3, 2, 1, 2, 3)
> y <- c(5, 7, 6, 8, 9, 6)
> order(x)                  ## 返回了排序的索引
[1] 1 4 3 5 2 6
> order(y)
[1] 1 3 6 2 4 5
> order(x, y)               ## 當向量x相同時，此時再依據y向量進行排序，即優先x排序，當x相同時，依據y排序， 當x為3時，此時y向量的6小於7，因此返回索引6.
[1] 1 4 3 5 6 2
> order(y, x)               ## 先y後x
 

[1] 1 3 6 2 4 5

2、例項

> name <- c('James','John','Luka','Green','Lisa','Curry','Jimmy','Xiaojie')
> R_scores <- c(88,68,76,76,93,76,98,98)
> Linux_scores <- c(78,63,76,82,81,63,92,95)
> scores <- data.frame(name=name,R_scores=R_scores,Linux_scores=Linux_scores)
> scores                    ## 測試資料框
 

     name R_scores Linux_scores
1   James       88           78
2    John       68           63
3    Luka       76           76
4   Green       76           82
5    Lisa       93           81
6   Curry       76           63
7   Jimmy       98           92
8 Xiaojie       98           95
> scores[order(scores$R_scores),]    ## 依據第二列進行排序
 

     name R_scores Linux_scores
2    John       68           63
3    Luka       76           76
4   Green       76           82
6   Curry       76           63
1   James       88           78
5    Lisa       93           81
7   Jimmy       98           92
8 Xiaojie       98           95
> scores[order(scores$R_scores, scores$Linux_scores),]   ## 優先依據第2列排序，當第二列有相同項時，再依據第三列進行排序
     name R_scores Linux_scores
2    John       68           63
6   Curry       76           63
3    Luka       76           76
4   Green       76           82
1   James       88           78
5    Lisa       93           81
7   Jimmy       98           92
8 Xiaojie       98           95

出處：https://mp.weixin.qq.com/s?__biz=MzAxMDkxODM1Ng==&mid=2247513582&idx=2&sn=77228bc56c3411e84afa457ff14425c4&chksm=9b4bf555ac3c7c434fa9c0cfe7d16744d6a361b3827aa930dbd334c36bc5d96336347067743e&mpshare=1&scene=23&srcid=0505TCPhIaQDpxUIBnPgUYtG&sharer_sharetime=1651685667859&sharer_shareid=50b75c6a886e09824b582fb782a7678b#rd