Values falling into different ranges in R

I have a grid grd of different ranges like this one:

> grd
   count  treshold
1   1      0.01
2   2      0.02
3   3      0.05
4   4      0.10
5   5      0.20

and a dataframe df like this one:

> df
    param   name
1   0.124   Tim
2   0.011   John
3   0.002   Alex
4   0.023   Jessica
5   0.056   Rose

I would like to use grd$treshold to add another column to the dataframe, df$bucket reporting which range the values in df$param fall into.

For instance the first value of param, 0.124, is higher than treshold, 0.10, then it will fall in count 5. The second one, 0.011, is between 0.01 and 0.02, then it will fall into count 2, and so on.

This is the final result:

> df
        param   name      bucket
    1   0.124   Tim         5
    2   0.011   John        2
    3   0.002   Alex        1
    4   0.023   Jessica     3
    5   0.056   Rose        4

A base solution with findInterval():

df$bucket <- findInterval(df$param, grd$treshold) + 1

df$bucket
# [1] 5 2 1 3 4

You can also use a rolling join with dplyr:

library(dplyr)

df %>%
  left_join(grd, by = join_by(closest(param < treshold))) %>%
  select(-treshold)

#   param    name count
# 1 0.124     Tim     5
# 2 0.011    John     2
# 3 0.002    Alex     1
# 4 0.023 Jessica     3
# 5 0.056    Rose     4

Data

grd <- read.table(text = "
count  treshold
1   1      0.01
2   2      0.02
3   3      0.05
4   4      0.10
5   5      0.20")

df <- read.table(text = "
param   name
1   0.124   Tim
2   0.011   John
3   0.002   Alex
4   0.023   Jessica
5   0.056   Rose")

Here is a possible solution using dplyr

library(dplyr)
df <- df |> 
  mutate(
    bucket = case_when(
      param <= 0.01 ~ 1,
      param <= 0.02 ~ 2,
      param <= 0.05 ~ 3,
      param <= 0.10 ~ 4,
      param <= 0.20 ~ 5
    )
  )

As far as I understood you question, the final result you shared in your question is not correct (row 2). If I misunderstood you can easily adjust the threshold parameters in case_when()