按组排序变量 (dplyr)

Question

我有一个带列的数据框 x1, x2, group我想生成一个带有额外列的新数据框 rank表示x1的顺序在其组中。

有相关问题here ，但已接受的答案似乎不再有效。

到这里为止，很好:

library(dplyr)
data(iris)
by_species <- iris %>% 
              arrange(Species, Sepal.Length) %>% 
              group_by(Species)  

但是当我尝试按组获得排名时:

by_species <- mutate(by_species, rank=row_number())

错误是:

Error in rank(x, ties.method = "first", na.last = "keep") :
argument "x" is missing, with no default

更新

问题是 dplyr 之间存在冲突和 plyr .要重现错误，请加载两个包:

library(dplyr)
library(plyr)
data(iris)
by_species <- iris %>% 
              arrange(Species, Sepal.Length) %>% 
              group_by(Species) %>% 
              mutate(rank=row_number())
# Error in rank(x, ties.method = "first", na.last = "keep") : 
# argument "x" is missing, with no default

卸货 plyr它可以正常工作:

detach("package:plyr", unload=TRUE)
by_species <- iris %>% 
              arrange(Species, Sepal.Length) %>% 
              group_by(Species) %>% 
              mutate(rank=row_number())

by_species %>% filter(rank <= 3)

##   Sepal.Length Sepal.Width Petal.Length Petal.Width    Species  rank
##          (dbl)       (dbl)        (dbl)       (dbl)     (fctr) (int)
## 1          4.3         3.0          1.1         0.1     setosa     1
## 2          4.4         2.9          1.4         0.2     setosa     2
## 3          4.4         3.0          1.3         0.2     setosa     3
## 4          4.9         2.4          3.3         1.0 versicolor     1
## 5          5.0         2.0          3.5         1.0 versicolor     2
## 6          5.0         2.3          3.3         1.0 versicolor     3
## 7          4.9         2.5          4.5         1.7  virginica     1
## 8          5.6         2.8          4.9         2.0  virginica     2
## 9          5.7         2.5          5.0         2.0  virginica     3

Answer 1

以下生成指定的所需结果。

library(dplyr)

by_species <- iris %>% arrange(Species, Sepal.Length) %>%
    group_by(Species) %>% 
    mutate(rank = rank(Sepal.Length, ties.method = "first"))

by_species %>% filter(rank <= 3)
##Source: local data frame [9 x 6]
##Groups: Species [3]
##
##  Sepal.Length Sepal.Width Petal.Length Petal.Width    Species  rank
##         (dbl)       (dbl)        (dbl)       (dbl)     (fctr) (int)
##1          4.3         3.0          1.1         0.1     setosa     1
##2          4.4         2.9          1.4         0.2     setosa     2
##3          4.4         3.0          1.3         0.2     setosa     3
##4          4.9         2.4          3.3         1.0 versicolor     1
##5          5.0         2.0          3.5         1.0 versicolor     2
##6          5.0         2.3          3.3         1.0 versicolor     3
##7          4.9         2.5          4.5         1.7  virginica     1
##8          5.6         2.8          4.9         2.0  virginica     2
##9          5.7         2.5          5.0         2.0  virginica     3

by_species %>% slice(1:3)
##Source: local data frame [9 x 6]
##Groups: Species [3]
##
##  Sepal.Length Sepal.Width Petal.Length Petal.Width    Species  rank
##         (dbl)       (dbl)        (dbl)       (dbl)     (fctr) (int)
##1          4.3         3.0          1.1         0.1     setosa     1
##2          4.4         2.9          1.4         0.2     setosa     2
##3          4.4         3.0          1.3         0.2     setosa     3
##4          4.9         2.4          3.3         1.0 versicolor     1
##5          5.0         2.0          3.5         1.0 versicolor     2
##6          5.0         2.3          3.3         1.0 versicolor     3
##7          4.9         2.5          4.5         1.7  virginica     1
##8          5.6         2.8          4.9         2.0  virginica     2
##9          5.7         2.5          5.0         2.0  virginica     3