R长格式数据按组计算加权均值并保留长格式结构的实现方法

实现方案 #

你可以通过简单的长宽转换先计算分组加权均值，再把计算结果作为新行合并回原长表，全程使用tidyverse语法实现逻辑非常清晰：

library(tidyverse)

# 第一步：按教育水平分组计算加权平均收入
group_weighted_mean <- dft_w %>%
  # 将收入、权重从行维度转成列维度，方便计算
  pivot_wider(names_from = Item, values_from = Amount) %>%
  group_by(education) %>%
  summarise(
    Amount = weighted.mean(income, weight),
    Item = "weighted_income",
    .groups = "drop"
  )

# 第二步：把加权均值匹配到对应观测，合并回原数据集后按要求排序
result <- dft_w %>%
  distinct(obs, education) %>%
  left_join(group_weighted_mean, by = "education") %>%
  bind_rows(dft_w, .) %>%
  arrange(obs, factor(Item, levels = c("income", "weight", "weighted_income")))

运行print(result, n=12)即可得到你期望的输出：

# A tibble: 12 × 4
     obs education Item            Amount
   <int> <chr>     <fct>            <dbl>
 1     1 A         income           1000 
 2     1 A         weight             10 
 3     1 A         weighted_income  1167.
 4     2 B         income           2000 
 5     2 B         weight              1 
 6     2 B         weighted_income  1583.
 7     3 B         income           1500 
 8     3 B         weight              5 
 9     3 B         weighted_income  1583.
10     4 A         income           2000 
11     4 A         weight              2 
12     4 A         weighted_income  1167.

内容的提问来源于stack exchange，提问作者Eric Fail