Question

我正在尝试使用连接字符串作为列名迭代地执行 dplyr 汇总

Category=c("a","a","b","b","b","c","c","c")
A1=c(1,2,3,4,3,2,1,2)
A2=c(10,11,12,13,14,15,16,17)
tt=cbind(Category,A1,A2)
tdat=data.frame(tt)
colnames(tdat)=c("Category","M1","M2")
ll=matrix(1:2,nrow=2)
for(i in 1:nrow(ll)) {
  Aone=tdat %>% group_by(Category) %>%
    summarize(Msum=sum(paste("M",i,sep="")))
}

我最终出现以下错误

x invalid 'type' (character) of argument
ℹ Input Msum is sum(paste("M", i, sep = "")).
ℹ The error occurred in group 1: Category = "A".
Run rlang::last_error() to see where the error occurred.```


The goal is to iteratively get arithmentic functions within summarize function in dplyr. But this concatenated string is not recognized as column name.

Answer 1

如果我们想传递一个字符串作为列名，则转换为 symbol 并计算 (!!)

library(dplyr)
Aone <- vector('list', nrow(ll))
for(i in seq_len(nrow(ll))) {
      Aone[[i]] <- tdat %>%
                    group_by(Category) %>%
                    summarize(Msum = sum(!! rlang::sym(paste("M", i, sep=""))))
    }

或者假设列名是'M-1'、'M-2'等，它应该也能工作

Aone <- vector('list', 2)
for(i in seq_along(Aone)) {
   Aone[[i]] <- tdat %>%
        group_by(Category) %>% 
       summarise(Msum = sum(!! rlang::sym(paste("M-", i, sep=""))), 
         .groups = 'drop')
  }

注意：原帖中的 ll 并不清楚。在这里，我们创建一个 list，其中 length 等于 'M-' 列的数量，并通过循环遍历该 {{1} 的序列将输出分配回 list 元素}

数据

list

将串联字符串作为 dplyr::summarise 中的列名传递

1 个答案:

数据