I have a dataframe named "data", as below :

and I would like to set thresholds and count how many ids are equal or below that threshold, which means a dataframe "results" like :

The only way I found to do this is to use "for" :

for(i in 1:10) {results$count[i] <- nrow(data[data$quantity <= i,]}

This instruction does work. However, with my real data, there are 500 thresholds and I have to repeat quite the same process 12 times... thus the "for" loop is very long to proceed. I couldn't find something to replace that, I would rather something like :

results$count <- nrow(data[data$quantity <= results$threshold,]

but it doesn't work ("longer object length is not a multiple of shorter object length"). Do you have some ideas?

CodePudding user response：

Try this:

library(tidyverse)

df <- tribble(
  ~id, ~quantity,
  "01", 5,
  "02", 3,
  "03", 7,
  "04", 4,
  "05", 9
)

result <- map_dfr(1:10, function(x){
  tibble(
    threshold = x,
    count = sum(df$quantity <= x)
    )
})

result
#> # A tibble: 10 × 2
#>    threshold count
#>        <int> <int>
#>  1         1     0
#>  2         2     0
#>  3         3     1
#>  4         4     2
#>  5         5     3
#>  6         6     3
#>  7         7     4
#>  8         8     4
#>  9         9     5
#> 10        10     5

^{Created on 2022-07-06 by the reprex package (v2.0.1)}