R:通过列名称向量对数据帧的列进行排序 [英] R: Sort columns of a data frame by a vector of column names
问题描述
我有一个数据框架,如下所示:
其中有1000个具有相似名称的列。
我有一个这样的列名称的向量,如下所示:
该向量按照cluster_id(最多可达11个)进行排序。
我想对数据框中的列进行排序,使列按照
我想要的一个简单的例子是:
数据:
ABC
1 2 3
4 5 6
$
$ b 矢量:
c(B,C,A)
排序:
BCA
2 3 1
5 6 4
有快速w ay这样做?
解决方案 Brodie的回答正是你要求的。但是,您意味着您的数据很大,所以我将使用data.table提供一个替代方法,它具有一个名为 setcolorder
的函数,它将通过引用更改列顺序
这是一个可重现的例子。
从一些简单的数据开始:
mydf< - data.frame(A = 1:2,B = 3:4,C = 5:6)
matches& data.frame(X = 1:3,Y = c(C,A,B),Z = 4:6)
mydf
#ABC
# 1 3 5
#2 2 4 6
匹配
#XYZ
#1 1 C 4
#2 2 A 5
#3 3 B 6
提供Brodie的回答的证明:
out< - mydf [matches $ Y]
out
#CAB
#1 5 1 3
#2 6 2 4
显示更高效的方式来做同样的事情。
library(data.table)
setDT(mydf)
mydf
#ABC
#1:1 3 5
#2:2 4 6
setcolorder(mydf,as.c hartes(匹配$ Y))
mydf
#CAB
#1:5 1 3
#2:6 2 4
/ pre>
I have a data.frame that looks like this:
which has 1000+ columns with similar names.
And I have a vector of those column names that looks like this:
The vector is sorted by the cluster_id (which goes up to 11).
I want to sort the columns in the data frame such that the columns are in the order of the names in the vector.
A simple example of what I want is that:
Data:
A B C
1 2 3
4 5 6
Vector:
c("B","C","A")
Sorted:
B C A
2 3 1
5 6 4
Is there a fast way to do this?
解决方案 Brodie's answer does exactly what you're asking for. However, you imply that your data are large, so I will provide an alternative using "data.table", which has a function called setcolorder
that will change the column order by reference.
Here's a reproducible example.
Start with some simple data:
mydf <- data.frame(A = 1:2, B = 3:4, C = 5:6)
matches <- data.frame(X = 1:3, Y = c("C", "A", "B"), Z = 4:6)
mydf
# A B C
# 1 1 3 5
# 2 2 4 6
matches
# X Y Z
# 1 1 C 4
# 2 2 A 5
# 3 3 B 6
Provide proof that Brodie's answer works:
out <- mydf[matches$Y]
out
# C A B
# 1 5 1 3
# 2 6 2 4
Show a more memory efficient way to do the same thing.
library(data.table)
setDT(mydf)
mydf
# A B C
# 1: 1 3 5
# 2: 2 4 6
setcolorder(mydf, as.character(matches$Y))
mydf
# C A B
# 1: 5 1 3
# 2: 6 2 4
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