I am trying to write a function
which will return all rows related to that id.
Input Data:
df <- data.frame(
id1=c('A1','A1','B1','B2','C2','C3','B3','D1','D2','E1'),
id2=c('P1','P2','P1','P2','P1','KK3','KK3','DL5','FD7','LO6')
)
E.g.
sample_rows <- function(id1){
#code here
return(output)
}
Desired Output 1:
sample_rows(id1='A1')
should return following data frame:
id1 id2
A1 P1
A1 P2
B1 P1
B2 P2
C2 P1
Desired Output 2:
sample_rows(id1 = 'C3')
should return following data frame:
id1 id2
C3 KK3
B3 KK3
Don't use sample
as function name, you risk overriding R own function
base R
solution:
my_fun <- function(id1) {
id2s <- df[df$id1 == id1, 'id2']
df[df$id2 %in% id2s,]
}
my_fun(id1 = 'A1')
#> id1 id2
#> 1 A1 P1
#> 2 A1 P2
#> 3 B1 P1
#> 4 B2 P2
#> 5 C2 P1
my_fun(id1 = 'C3')
#> id1 id2
#> 6 C3 KK3
#> 7 B3 KK3
dplyr
solution:
library(dplyr)
my_dplyr_fun <- function(data, id1) {
id2s <- filter(data, id1 == {{id1}}) %>%
pull(id2)
data %>%
filter(id2 %in% id2s)
}
df %>%
my_dplyr_fun('C3')
#> id1 id2
#> 1 C3 KK3
#> 2 B3 KK3
Created on 2020-04-03 by the reprex package (v0.3.0)