条件满足时的行总和-R中的data.frame [英] sum of rows when condition is met- data.frame in R

问题描述

df
  var1 var2
1    a    1
2    b    2
3    a    3
4    c    6
5    d   88
6    b    0

df2 <- data.frame(var1=c("k","b","a","k","k","b"),var2=c(14,78,5,6,88,0))
> list <- list(df,df2)

for(i in list){
   if(any(i[ ,1] == i[ ,1})){
      cumsum(.)
   }
}

我有一个包含data.frames的列表.我想遍历这些data.frames.如果第一列中有相同的字母，则应计算总和.我希望此新行在我的data.frame中. 我完全搞砸了if statement.有人可以帮我吗?

I have a list containing of data.frames. I want to iterate over these data.frames. When there is the same letter in the first column, then the sum should be calculated. I want this new row to be in my data.frame. I completely messed up the if statement. Can somebody help me please?

结果应类似于

df
  var1 var2
1 a    4
2 b    2
3 c    6
4 d    88

以及df2

var1 var2
1    k   108
2    b   78
3    a    5

在我真正的问题中，列表由10个data.frames组成，而不仅仅是两个

In my real problem, the list consists of 10 data.frames, not just two

推荐答案

在Base-R中

sapply(split(df$var2,df$var1), sum)

 a  b  c  d 
 4  2  6 88 

或在数据框列表的每个元素上执行

or to do it on each element of a list of dataframes

lapply(list, function(x) sapply(split(x$var2,x$var1), sum))

[[1]]
 a  b  c  d 
 4  2  6 88 

[[2]]
  a   b   k 
  5  78 108 

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