dplyr 用小计总结 [英] dplyr summarize with subtotals

问题描述

Excel 中数据透视表的一大优点是它们会自动提供小计.首先，我想知道在 dplyr 中是否已经创建了可以完成此操作的任何内容.如果没有，实现它的最简单方法是什么?

One of the great things about pivot tables in excel is that they provide subtotals automatically. First, I would like to know if there is anything already created within dplyr that can accomplish this. If not, what is the easiest way to achieve it?

在下面的示例中，我按气缸和化油器的数量显示了平均排量.对于每组气缸 (4,6,8)，我想查看该组的平均位移(或总位移，或任何其他汇总统计数据).

In the example below, I show the mean displacement by number of cylinders and carburetors. For each group of cylinders (4,6,8), I'd like to see the mean displacement for the group (or total displacement, or any other summary statistic).

library(dplyr)
mtcars %>% group_by(cyl,carb) %>% summarize(mean(disp))

  cyl carb mean(disp)
1   4    1      91.38
2   4    2     116.60
3   6    1     241.50
4   6    4     163.80
5   6    6     145.00
6   8    2     345.50
7   8    3     275.80
8   8    4     405.50
9   8    8     301.00

推荐答案

data.table 很笨拙，但这是一种方法:

data.table It's very clunky, but this is one way:

library(data.table)
DT <- data.table(mtcars)
rbind(
  DT[,.(mean(disp)),          by=.(cyl,carb)],
  DT[,.(mean(disp), carb=NA), by=.(cyl) ],
  DT[,.(mean(disp), cyl=NA),  by=.(carb)]
)[order(cyl,carb)]

这给了

    cyl carb       V1
 1:   4    1  91.3800
 2:   4    2 116.6000
 3:   4   NA 105.1364
 4:   6    1 241.5000
 5:   6    4 163.8000
 6:   6    6 145.0000
 7:   6   NA 183.3143
 8:   8    2 345.5000
 9:   8    3 275.8000
10:   8    4 405.5000
11:   8    8 301.0000
12:   8   NA 353.1000
13:  NA    1 134.2714
14:  NA    2 208.1600
15:  NA    3 275.8000
16:  NA    4 308.8200
17:  NA    6 145.0000
18:  NA    8 301.0000

我更愿意看到类似 R table 的结果，但不知道有什么函数可以实现.

I'd rather see results in something like an R table, but don't know of any functions for that.

dplyr @akrun 发现了这个类似的代码

dplyr @akrun found this analogous code

bind_rows(
  mtcars %>% 
    group_by(cyl, carb) %>% 
    summarise(Mean= mean(disp)), 
  mtcars %>% 
    group_by(cyl) %>% 
    summarise(carb=NA, Mean=mean(disp)), 
  mtcars %>% 
    group_by(carb) %>% 
    summarise(cyl=NA, Mean=mean(disp))
) %>% arrange(cyl, carb)

我们可以将重复操作包装在一个函数中

We could wrap the repeat operations in a function

library(lazyeval)
f1 <- function(df, grp, Var, func){
  FUN <- match.fun(func)
   df %>% 
     group_by_(.dots=grp) %>%
     summarise_(interp(~FUN(v), v=as.name(Var)))
  }

 m1 <- f1(mtcars, c('carb', 'cyl'), 'disp', 'mean')
 m2 <- f1(mtcars, 'carb', 'disp', 'mean')
 m3 <- f1(mtcars, 'cyl', 'disp', 'mean')

 bind_rows(list(m1, m2, m3)) %>%
              arrange(cyl, carb) %>%
              rename(Mean=`FUN(disp)`)
   carb cyl     Mean
1     1   4  91.3800
2     2   4 116.6000
3    NA   4 105.1364
4     1   6 241.5000
5     4   6 163.8000
6     6   6 145.0000
7    NA   6 183.3143
8     2   8 345.5000
9     3   8 275.8000
10    4   8 405.5000
11    8   8 301.0000
12   NA   8 353.1000
13    1  NA 134.2714
14    2  NA 208.1600
15    3  NA 275.8000
16    4  NA 308.8200
17    6  NA 145.0000
18    8  NA 301.0000

<小时>

使用 data.table 的 rbindlist 和 fill 可以使任一选项不那么难看:

---

Either option can be made a little less ugly with data.table's rbindlist with fill:

rbindlist(list(
  mtcars %>% group_by(cyl) %>% summarise(mean(disp)),
  mtcars %>% group_by(carb) %>% summarise(mean(disp)),
  mtcars %>% group_by(cyl,carb) %>% summarise(mean(disp))
),fill=TRUE) %>% arrange(cyl,carb)

rbindlist(list(
  DT[,mean(disp),by=.(cyl,carb)],
  DT[,mean(disp),by=.(cyl)],
  DT[,mean(disp),by=.(carb)]
),fill=TRUE)[order(cyl,carb)]

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