如何按多个列对数据框进行排序 [英] How to sort a dataframe by multiple column(s)

问题描述

我想按多个列对data.frame进行排序.例如，对于下面的data.frame，我想按列z(降序)然后按列b(升序)进行排序:

I want to sort a data.frame by multiple columns. For example, with the data.frame below I would like to sort by column z (descending) then by column b (ascending):

dd <- data.frame(b = factor(c("Hi", "Med", "Hi", "Low"), 
      levels = c("Low", "Med", "Hi"), ordered = TRUE),
      x = c("A", "D", "A", "C"), y = c(8, 3, 9, 9),
      z = c(1, 1, 1, 2))
dd
    b x y z
1  Hi A 8 1
2 Med D 3 1
3  Hi A 9 1
4 Low C 9 2

推荐答案

您可以使用

You can use the order() function directly without resorting to add-on tools -- see this simpler answer which uses a trick right from the top of the example(order) code:

R> dd[with(dd, order(-z, b)), ]
    b x y z
4 Low C 9 2
2 Med D 3 1
1  Hi A 8 1
3  Hi A 9 1

大约2年后再只是按列索引询问如何执行此操作.答案是将所需的排序列简单地传递给order()函数:

Edit some 2+ years later: It was just asked how to do this by column index. The answer is to simply pass the desired sorting column(s) to the order() function:

R> dd[order(-dd[,4], dd[,1]), ]
    b x y z
4 Low C 9 2
2 Med D 3 1
1  Hi A 8 1
3  Hi A 9 1
R> 

而不是使用列名(和with()可以更轻松/更直接地访问).

rather than using the name of the column (and with() for easier/more direct access).

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