how to get a seq of 5 from 0 instead from min to max

March 8, 2022

I have df that looks like following. I would like to build new variable break following rule:
if max>60, then break includes (0, min, max, and the numbers +/-10 from 0);
if max<=60, then break includes (0, min, max, and the numbers +/-7 from 0).

I might not describe this clearly. but you can see the expected outcome here:

what should I do? The tricky part is I need to get the seq from 0 +/-10, not from min to max, every 10.

df<-structure(list(min = c(-9, -18, 3), max = c(49, 62, 18)), row.names = c(NA, 
-3L), class = c("tbl_df", "tbl", "data.frame"))

>Solution :

get_seq <- function(mn,mx,val) {
  vals = unique(c(mn, mx, -1*seq(0,abs(mn),by=val),seq(0,mx,val)))
  vals[order(vals)]
}
df %>% rowwise() %>% 
  mutate(break_seq = case_when(
    max>60~list(get_seq(min,max,10)),
    max<=60~list(get_seq(min,max,7))
  )
)

Output:

    min   max break_seq 
  <dbl> <dbl> <list>    
1    -9    49 <dbl [10]>
2   -18    62 <dbl [10]>
3     3    18 <dbl [5]>

Or, if you want a character string of those numbers, you could do something like this:

get_seq <- function(mn,mx,val) {
  vals = unique(c(mn, mx, -1*seq(0,abs(mn),by=val),seq(0,mx,val)))
  paste0(vals[order(vals)], collapse=",")
}
df %>% rowwise() %>% 
  mutate(break_seq = case_when(
    max>60~get_seq(min,max,10),
    max<=60~get_seq(min,max,7)
  )
)

Output:

    min   max break_seq                     
  <dbl> <dbl> <chr>                         
1    -9    49 -9,-7,0,7,14,21,28,35,42,49   
2   -18    62 -18,-10,0,10,20,30,40,50,60,62
3     3    18 0,3,7,14,18