将数据帧中的列重新排列为指定的顺序 [英] Reorder a column in a dataframe to a specified order

问题描述

我有一个数据帧，每行都有一个值，每行100行都有一个索引（介于1到10之间）。我想以特定的顺序对索引块进行排序，但不确定如何执行：

  N = 1000 
 value = runif（N，min = 0，max = 100）
 index = rep（1:10，each = 100）
 DF = data.frame（value，index）
 ord = c（1,4,6,3,7,9,8,2,5,10）
  

所以基本上，我希望DF的索引列按照ord中指定的顺序排序，而不是DF的索引列被排序为1,2,3,4,5,6,7， 8,9,10。

任何建议将不胜感激！

解决方案

p>您可以简单地将 index 转换为 ord 中的级别，然后将数据排序为

  DF $ index<  -  factor（DF $ index，levels = ord）
 DF [order（DF $索引），] 
  

如果您不想改变原始数据 em>您可以简单地创建一个单独的索引，如

  indx<  -  factor（DF $ ind ex，levels = ord）
 DF [order（indx），] 
  

通过 setorder 从 data.table 包

$中的引用订购您的数据集b $ b

  library（data.table）
 setorder（setDT（DF）[，index：= factor（index，levels = ord）]，index）
  

I have a data frame, where every row has a value, and every block of 100 rows has an index (between 1 and 10). I would like to sort the index blocks in a particular order, but am unsure how to do that:

N=1000
value = runif(N, min=0, max=100)
index = rep(1:10, each=100)
DF=data.frame(value,index)
ord = c(1,4,6,3,7,9,8,2,5,10)

So basically, I would like the index column of DF to be ordered in blocks of the order specified in ord, instead of the index column of DF being ordered as 1,2,3,4,5,6,7,8,9,10.

Any advice would be appreciated!

解决方案

You could simply convert index to factor and set the levels as in ord order and then sort the data as in

DF$index <- factor(DF$index, levels = ord)
DF[order(DF$index), ]

If you don't want to "alter your original data" you could simply create a separate index as in

indx <- factor(DF$index, levels = ord) 
DF[order(indx), ]

Additional otion is to order your data set by reference using setorder from the data.table package

library(data.table)
setorder(setDT(DF)[, index := factor(index, levels = ord)], index)

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