[英]How can I summarise numbers of levels (nlevels) in grouped data using dplyr?
分组后,我想使用dplyr中的summary函数为数据框中的每个变量提取级别数。 这是数据帧的副本:
x=c("A","A","A","A","A","B","B","B","B","C","C","C","D","D","D","E","E")
y=c("a","b","c","a","b","a","b","c","d","c","b","e","b","d","f","a","b")
z=c("x","x","x","y","y","p","p","p","p","t","v","v","m","m","n","o","o")
d=data.frame(x,y,z)
这是我正在使用的代码
library(dplyr)
d %>%
group_by(x) %>%
summarise(total=n(),
Y=nlevels(y),
Z=nlevels(z))
但是,这会生成Y和Z列,这些列汇总了数据帧d中而不是分组数据中的级别。
我想生成的数据帧如下所示:
x=c("A","B","C","D","E")
total=c(5,4,3,3,2)
Y=c(3,4,3,3,2)
Z=c(2,1,2,2,1)
d2=data.frame(x,total,Y,Z)
d2
谢谢!
为此,您需要n_distinct
:
d %>%
group_by(x) %>%
summarise(total = n(),
Y = n_distinct(y),
Z = n_distinct(z))
结果:
# A tibble: 5 x 4
x total Y Z
<fctr> <int> <int> <int>
1 A 5 3 2
2 B 4 4 1
3 C 3 3 2
4 D 3 3 2
5 E 2 2 1
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