用r data.table中的Factor替换值 [英] Replace value with Factor in r data.table

问题描述

我有一个数据集，其中包含一个因子（在示例中为cut）的列。它目前设置如下：

 库（ggplot2）＃访问钻石数据集
库）
 data<  -  data.table（diamonds）[，list（mean_carat = mean（carat）），by = c（'cut'，'color'）] 
  

我试图将名为Fair的所有条目更改为Good，因为在我的数据集中，这两个条目实际上是相同的，不同。我一直试图使用的语法是：

  data [which（cut =Fair），cut：= Good] 
  

，输出为

 >错误：data [which（cut =Fair），cut：=Good]中的意外符号
  pre> 
 
 
任何人都可以告诉我我在哪里出错？
解决方案
您使用 = 而不是 == 。尝试
  data [which（cut ==Fair），cut：=Good] 
  
你也不需要其中语句：
  data [cut ==Fair，cut：=Good] 
  pre> 
I have a data set that has a column for a factor (in the example case, cut). It is currently set up like this:
library(ggplot2) # access to diamonds dataset
library(data.table)
data <- data.table(diamonds)[,list(mean_carat=mean(carat)), by=c('cut', 'color')]
I am trying to change all entries named "Fair" to "Good" because in my data set, the two entries are actually the same thing but notated differently. The syntax that I have been trying to use is:
data[which(cut = "Fair"), cut := "Good"]
and the output is
>Error: unexpected symbol in "data[which(cut = "Fair"), cut := "Good"]"
Can anyone tell me where I am going wrong?
解决方案
You used = instead of ==. Try 
data[which(cut == "Fair"), cut := "Good"]
You also don't actually need the which statement: 
data[cut == "Fair", cut := "Good"]


                        
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