按多列对数据框行进行排序(排序) [英] Sort (order) data frame rows by multiple columns

问题描述

我想按多列对数据框进行排序.例如，对于下面的数据框，我想按列z"(降序)然后按列b"(升序)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 order() 无需借助附加工具即可直接运行 - 请参阅此更简单的答案，该答案使用了 order() 顶部的技巧代码>示例(订单) 代码:

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 只是通过列索引询问如何执行此操作.答案是简单地将所需的排序列传递给 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> 

而不是使用列的名称(和 with() 以便更容易/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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