问题描述
我试图弄清如何根据另一列中的多列对一个data.frame进行排序.这个问题可以和向量一起使用 .有人可以建议一种与data.frames等效的方法吗?
I'm trying to make sense of how to sort one data.frame based on multiple columns in another. This question does this with vectors. Can someone suggest a way to do the equivalent with data.frames?
这是一些示例数据.
x1 <- data.frame(a=1:5, b=letters[1:5], c=rnorm(5))
x2 <- data.frame(a=c(4,4,2), b=c("d", "d", "b"), d=rnorm(3))
所以我想按x1的前两列对x2进行排序.我的实际数据要复杂得多，但这重复了这个想法...
So I want to sort x2 by the first two columns of x1. My actual data is much more complicated, but this replicates the idea...
推荐答案
这实际上取决于您的数据的真实外观.现在看来，您只需要对一列进行排序，就可以轻松地做到这一点:
It really depends on what your data really looks like. As it looks right now, you only need one column to sort, and that is easily done by:
x2[order(match(x2[,1],x1[,1])),]
如果您需要多个列，这将变得有些棘手.您必须指定要首先排序的那个，然后是第二个，例如:
If you need more than one column, this becomes a bit trickier. You will have to specify which one you want to sort first on, and which one second, eg :
x1 <- data.frame(a=rep(1:3,2), b=rep(letters[2:4],each=2), c=rnorm(6))
x2 <- data.frame(a=c(3,3,2), b=c("c", "d", "b"), d=rnorm(3))
x2[order(match(
paste(x2[,1],x2[,2]),
paste(x1[,1],x1[,2]))
),]
它首先在第一列上排序，然后在第二列上排序.您必须记住，x2中也需要x2中的所有组合. T
This sorts on the first column first, and then on the second. You have to keep in mind that you need all combinations in x2 also in x1. T
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