R语言DataFrame按类别合并指定行生成新行的实现问题

你的代码存在几个问题：

• 索引语法错误：c=1,2,3,6写法不正确，正确的向量索引应为c(1,2,3,6)
• 列名不匹配：原数据的重量列是kg，你写的total会新增不匹配的列，导致数据结构冲突
• 缺少删除原水果行的步骤

下面提供两种易懂的解决方式：

方法一：分步操作（适合新手理解） #

library(tidyverse)

# 原始数据
data <- data.frame(
  "food"= c("Banana", "Orange", "Apple", "Meat", "Fish", "Cherries", "Wheat"),
  "kg"= c(2,3,1,2,6,4,5)
)

# 1. 计算指定水果的kg总和（用食物名称匹配比索引更可靠，避免行顺序变化出错）
fruit_total <- sum(data$kg[data$food %in% c("Banana", "Orange", "Apple", "Cherries")])

# 2. 添加新行，确保列名和原数据一致
data <- data %>%
  add_row(food = "Fruits", kg = fruit_total)

# 3. 过滤掉原来的水果行，保留汇总行和其他食物
data <- data %>%
  filter(!food %in% c("Banana", "Orange", "Apple", "Cherries"))

方法二：链式简洁操作 #

library(tidyverse)

data <- data.frame(
  "food"= c("Banana", "Orange", "Apple", "Meat", "Fish", "Cherries", "Wheat"),
  "kg"= c(2,3,1,2,6,4,5)
)

data <- data %>%
  # 先保留非水果行
  filter(!food %in% c("Banana", "Orange", "Apple", "Cherries")) %>%
  # 追加汇总的水果行
  add_row(
    food = "Fruits",
    kg = sum(data$kg[data$food %in% c("Banana", "Orange", "Apple", "Cherries")])
  )

运行后得到的结果：

food kg
1   Meat  2
2   Fish  6
3  Wheat  5
4 Fruits 10

内容的提问来源于stack exchange，提问作者RebecaOdC