Find which interval row in a data frame that each element of a vector belongs in

Question

I have a vector of numeric elements, and a dataframe with two columns that define the start and end points of intervals. Each row in the dataframe is one interval. I want to

Answer 1

For completion sake, here is another way, using the intervals package:

library(tidyverse)
elements <- c(0.1, 0.2, 0.5, 0.9, 1.1, 1.9, 2.1)

intervalsDF <- 
  frame_data(  ~phase, ~start, ~end,
               "a",     0,      0.5,
               "b",     1,      1.9,
               "c",     2,      2.5
  )

library(intervals)
library(rlist)

interval_overlap(
  Intervals(intervalsDF %>% select(-phase) %>% as.matrix, closed = c(TRUE, TRUE)),
  Intervals(data_frame(start = elements, end = elements), closed = c(TRUE, TRUE))
) %>% 
  list.map(data_frame(interval_index = .i, element_index = .)) %>% 
  do.call(what = bind_rows)

# A tibble: 6 × 2
#  interval_index element_index
#                    
#1              1             1
#2              1             2
#3              1             3
#4              2             5
#5              2             6
#6              3             7