如何根据R中另一列的特定值正确更改级别值？

发布于 2025-01-25 21:44:35 字数 721 浏览 4 评论 0原文

我想根据同一列的特定值和另一列的特定值更改/重新编码列的级别。例如，让我们使用ggplot2 ::钻石。在这种情况下，我想在剪切列中更改“ premium”的价值，如果列 color 是“ d”，如果列 color 是“ j”，则将“ prem”的值更改为“惊人”。这是我的尝试：

df <- ggplot2::diamonds
unique(df$cut) #to look at the initial values


df$cut <- with(df,ifelse(cut == "Premium" & color == "D", "Perfect", 
                      ifelse(cut== "Premium" & color == "J","Amazing", cut)))

问题是，随后查看剪切列时，其他值也已更改。

unique(df$cut)

[1] "5"       "4"       "2"       "3"       "1"       "Perfect" "Amazing"

有人可以告诉我我在这里做错了什么吗？如果除了我尝试这样做之外还有其他方法，我也很感谢您看到这一点！

原文

I want to change/recode the levels for a column based on a specific value of the same column and another column. As an example, let's use ggplot2::diamonds. In this scenario, I want to change the value of "Premium" in the cut column to "Perfect" if the column color is "D" and change the value of "Premium" to "Amazing" if column color is "J". This is my attempt:

df <- ggplot2::diamonds
unique(df$cut) #to look at the initial values


df$cut <- with(df,ifelse(cut == "Premium" & color == "D", "Perfect", 
                      ifelse(cut== "Premium" & color == "J","Amazing", cut)))

The issue is that when looking at the cut column afterwards, the other values have also been changed.

unique(df$cut)

[1] "5"       "4"       "2"       "3"       "1"       "Perfect" "Amazing"

Can someone please tell me what I am doing wrong here? If there are other ways than how I attempted to do this, I would also appreciate seeing that as well!

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稚然 2025-02-01 21:44:35

使用case_when（）：

library(dplyr)
df <- df %>% 
  mutate(cut = 
           as.factor(case_when(
    (cut == "Premium" & color == "D") ~ "Perfect",
    (cut == "Premium" & color == "J") ~ "Amazing",
    TRUE  ~ as.character(cut))
  )
  ) 

unique(df$cut)

输出：

[1] Ideal     Premium   Good      Very Good Fair      Perfect   Amazing  
Levels: Amazing Fair Good Ideal Perfect Premium Very Good

Using case_when():

library(dplyr)
df <- df %>% 
  mutate(cut = 
           as.factor(case_when(
    (cut == "Premium" & color == "D") ~ "Perfect",
    (cut == "Premium" & color == "J") ~ "Amazing",
    TRUE  ~ as.character(cut))
  )
  ) 

unique(df$cut)

Output:

[1] Ideal     Premium   Good      Very Good Fair      Perfect   Amazing  
Levels: Amazing Fair Good Ideal Perfect Premium Very Good

回复收藏 0 原文

漆黑的白昼 2025-02-01 21:44:35

我经常使用此base r方法：

df$cut <- as.character(df$cut)

df$cut[df$color == "D" & df$cut == "Premium" ] <-  "Perfect"
df$cut[df$color == "J" & df$cut == "Premium" ] <-  "Amazing"

df$cut <- as.ordered(df$cut)

但是您必须先将因子转换为字符，否则您会遇到错误。

I often use this base R method:

df$cut <- as.character(df$cut)

df$cut[df$color == "D" & df$cut == "Premium" ] <-  "Perfect"
df$cut[df$color == "J" & df$cut == "Premium" ] <-  "Amazing"

df$cut <- as.ordered(df$cut)

But you have to turn your factor to character first, or you will get an error.

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