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

Another base method (mostly):

# we need this for the last line - if you don't use magrittr, just wrap the sapply around the lapply
library(magrittr)

# get a list of vectors where each item is whether an item's location in y is ok in each to/from in x
locationok  <- lapply(y$location, function(z) z >= x$from & z <= x$to)

# another list of logical vectors indicating whether y's location matches the number in x
idok  <- lapply(y$id_number, function(z) z== x$number)

# combine the two list and use the combined vectors as an index on x$name
lapply(1:nrow(y), function(i) {
      x$name[ locationok[[i]] & idok[[i]]  ]
}) %>% 
# replace zero length strings with NA values
sapply( function(x) ifelse(length(x) == 0, NA, x)