Create dyadic (relational) data from monadic data

Question

I have conflict data that looks like this

conflict_ID country_code   SideA
1              1             1          
1              2             1 
1              3             0
2              4             1
2              5             0 

Now I want to make it into dyadic conflict data that looks like this (SideA=1 should be country_code_1):

conflict_ID country_code_1 country_code_2 
1              1             3          
1              2             3 
2              4             5

Can anyone point me in the right direction?

Answer 1

Here's a direct approach:

df %>%
  filter(SideA == 1) %>%
  select(conflict_ID, country_code_1 = country_code) %>%
  left_join(
    df %>%
      filter(SideA == 0) %>%
      select(conflict_ID, country_code_2 = country_code),
    by = "conflict_ID"
  )
#   conflict_ID country_code_1 country_code_2
# 1           1              1              3
# 2           1              2              3
# 3           2              4              5

Using this data:

df = read.table(text = 'conflict_ID country_code   SideA
1              1             1          
1              2             1 
1              3             0
2              4             1
2              5             0 ', header = T)