3.3.4 列と行の集計

列と行を集計するOREdplyr関数。

表3-5 列と行の集計

関数	説明
count count	グループ別に行をカウントします。tallyと似ていますが、group_byを実行します。
summarise summarise_	集計関数を使用して、列をまとめます。ore.frameオブジェクトをグループ化すると、集計関数がグループ単位で適用されます。結果のore.frameは、入力ore.frameの1つのグループ化を削除します。
tally	グループ別に行を集計します。最初の集計か再集計に応じてnまたはsum(n)をコールするsummariseの便利なラッパーです。

例3-74 列の集計

次の例では、mtcars data.frameオブジェクトでore.push関数を使用して作成されるore.frameオブジェクトMTCARSを使用します。集計関数count、summarizeおよびtallyの使用例を示します。また、OREdplyr関数arrangeおよびgroup_byも使用します。

MTCARS <- ore.push(mtcars)
arrange(tally(group_by(MTCARS, cyl)), cyl)
tally(group_by(MTCARS, cyl), sort = TRUE)

# Multiple tallys progressively roll up the groups
cyl_by_gear <- tally(group_by(MTCARS, cyl, gear), sort = TRUE)
tally(cyl_by_gear, sort = TRUE)
tally(tally(cyl_by_gear))

cyl_by_gear <- tally(group_by(MTCARS, cyl, gear), wt = hp, sort = TRUE)
tally(cyl_by_gear, sort = TRUE)
tally(tally(cyl_by_gear))

cyl_by_gear <- count(MTCARS, cyl, gear, wt = hp + mpg, sort = TRUE)
tally(cyl_by_gear, sort = TRUE)
tally(tally(cyl_by_gear))

# Load the magrittr library to use the forward-pipe operator %>%
library(magrittr)
MTCARS %>% group_by(cyl) %>% tally(sort = TRUE)

# count is more succinct and also does the grouping
MTCARS %>% count(cyl) %>% arrange(cyl)
MTCARS %>% count(cyl, wt = hp) %>% arrange(cyl)
MTCARS %>% count_("cyl", wt = hp, sort = TRUE)

この例のリスト

R> MTCARS <- ore.push(mtcars)
R> arrange(tally(group_by(MTCARS, cyl)), cyl)
  cyl  n
1   4 11
2   6  7
3   8 14
R> tally(group_by(MTCARS, cyl), sort = TRUE)
  cyl  n
1   8 14
2   4 11
3   6  7
R> 
R> # Multiple tallys progressively roll up the groups
R> cyl_by_gear <- tally(group_by(MTCARS, cyl, gear), sort = TRUE)
R> tally(cyl_by_gear, sort = TRUE)
Using n as weighting variable
  cyl  n
1   8 14
2   4 11
3   6  7
R> tally(tally(cyl_by_gear))
Using n as weighting variable
Using n as weighting variable
 n 
32 
R>
R> cyl_by_gear <- tally(group_by(MTCARS, cyl, gear), wt = hp, sort = TRUE)
R> tally(cyl_by_gear, sort = TRUE)
Using n as weighting variable
  cyl    n
1   8 2929
2   4  909
3   6  856
R> tally(tally(cyl_by_gear))
Using n as weighting variable
Using n as weighting variable
   n 
4694 
R> 
R> cyl_by_gear <- count(MTCARS, cyl, gear, wt = hp + mpg, sort = TRUE)
R> tally(cyl_by_gear, sort = TRUE)
Using n as weighting variable
  cyl      n
1   8 3140.4
2   4 1202.3
3   6  994.2
R> tally(tally(cyl_by_gear))
Using n as weighting variable
Using n as weighting variable
     n 
5336.9 
R> 
R> # Load the magrittr library to use the forward-pipe operator %>%
R> library(magrittr)
R> MTCARS %>% group_by(cyl) %>% tally(sort = TRUE)
  cyl  n
1   8 14
2   4 11
3   6  7
R> 
R> # count is more succinct and also does the grouping
R> MTCARS %>% count(cyl) %>% arrange(cyl)
  cyl  n
1   4 11
2   6  7
3   8 14
R> MTCARS %>% count(cyl, wt = hp) %>% arrange(cyl)
  cyl    n
1   4  909
2   6  856
3   8 2929
R> MTCARS %>% count_("cyl", wt = hp, sort = TRUE)
  cyl    n
1   8 2929
2   4  909
3   6  856