如何将r中同一组的多个变量的值相加

Question

我需要对同一组中大约 40 个变量的值求和。

这是一个示例数据集。所以我想按地区和部门对 score1-score5 的值求和。

region <- rep(c("south", "east", "west", "north"),times=10)
department <- rep(c("A",  "B","C","D","E"),times=8)
score1 <- rnorm(n = 40, mean = 0, sd = 1)
score2 <-rnorm(n = 40, mean = 3, sd = 1.5)
score3 <-rnorm(n = 40, mean = 2, sd = 1)
score4 <-rnorm(n = 40, mean = 1, sd = 1.5)
score5 <-rnorm(n = 40, mean = 5, sd = 1.5)
df <- data.frame(region, department, score1, score2, score3, score4, score5)

这是导致我想要的结果的代码，但有没有更简单的方法来做到这一点：

df %>% group_by(region, department) %>%
       summarise(score1=sum(score1), 
                score2=sum(score2),
                score3=sum(score3),
                score4=sum(score4),
                score5=sum(score5))

我尝试使用循环，但这不起作用：

vlist<-c("score1", "score2", "score3", "score4", "score5")
for (var in vlist) {
  df<-df %>% group_by(region, department) %>%
    summarise(var=sum(.[[var]]))
}

还有其他方法或我的循环有什么问题吗？ 谢谢！

Answer 1

使用across - 循环across starts_with 'score' 的列并获取sum

library(dplyr)
out1 <- df %>% 
   group_by(region, department) %>% 
   summarise(across(starts_with('score'), sum), .groups = 'drop')

---

在for 循环中，问题在于df 在每次迭代中都会更新（df <-..），summarise仅返回 group by 中提供的列和总结输出。因此，在第一次迭代之后，'df' 根本就没有'score' 列。如果我们想使用for 循环，请在list 中获取输出，然后在reduce 中使用连接

library(purrr) 
out_list <- vector('list', length(vlist))
names(out_list) <- vlist
for (var in vlist) {
    out_list[[var]] <- df %>% 
            group_by(region, department) %>%
            summarise(!!var := sum(cur_data()[[var]]), .groups = 'drop')
   }
out2 <- reduce(out_list, full_join, by = c('region', 'department'))

-检查输出

> identical(out1, out2)
[1] TRUE