r - 在 R 中，一个变量如何在另一个变量下分支多个变量？

Question

我试图通过一组变量将我的观察结果分组到另一组变量下，最后一组变量下。这是我的例子:

     country      name     ethnicity   party

     Afghanistan  john     Pashtun     X Party
     Afghanistan  oliver   Pashtun     Y Party
     Afghanistan  brad     Tajik       X Party
     Afghanistan  chad     Hazara      X Party
     Bosnia       virgin   Serb        P Party
     Bosnia       mary     Serb        P Party
     Bosnia       jesus    Croat       C Party

我要做的应该是创建每个政党下所有现有种族的集合，并计算一个政党、一个国家内每个种族下有多少人，看起来像这样:

     country      party     ethnicity   count

     Afghanistan  X Party   Pashtun     1
     Afghanistan  X Party   Tajik       1
     Afghanistan  X Party   Hazara      1
     Afghanistan  Y Party   Pashtun     1
     Afghanistan  Y Party   Tajik       0
     Afghanistan  Y Party   Hazara      0
     Bosnia       P Party   Serb        2
     Bosnia       P Party   Croat       0
     Bosnia       C Party   Serb        0
     Bosnia       C Party   Croat       1

到目前为止，我已经尝试了 group_by 和 aggregate 函数，但没有成功。

Answer 1

这是一个非常简单的操作，请阅读本书https://r4ds.had.co.nz/

library(data.table)
library(tidyverse)

df_example <- fread("country      name     ethnicity   party coolness
Afghanistan  john     Pashtun     X_Party     cool
Afghanistan  oliver   Pashtun     Y_Party     not_cool
Afghanistan  brad     Tajik       X_Party     cool
Afghanistan  chad     Hazara      X_Party     not_cool
Bosnia       virgin   Serb        P_Party     cool
Bosnia       mary     Serb        P_Party     cool
Bosnia       jesus    Croat       C_Party     not_cool" ,

                    header = TRUE)


df_example %>% 
  group_by(country,ethnicity,party) %>% 
  add_tally() %>% 
  select(-name) %>% # Some stuff that you don't want
  distinct()