R: Check if value from dataframe is within range other dataframe

Question

I am looking for a way to look up infromation from 1 dataframe in another dataframe, get a value from that other dataframe and pass it back to the first frame..

exam

Answer 1

Since you want to match the columns of id_number and number, you can join x and y on the columns and then mutate the name to NA if the location doesn't fall between from and to, here is a dplyr option:

library(dplyr)
y %>% left_join(x, by = c("id_number" = "number")) %>% 
      mutate(name = if_else(location >= from & location <= to, as.character(name), NA_character_)) %>% 
      select(-from, -to) %>% arrange(name) %>% 
      distinct(location, id_number, .keep_all = T)

#   location id_number     name
# 1      1.5        30 region 1
# 2      2.8        30 region 2
# 3      2.0        36 region 7
# 4     10.0        38     
# 5      3.5        40