seq can only use a single value in the by parameter. Is there a way to vectorize by, i.e. to use multiple intervals?
Something like this:
seq(1, 10, by = c(1, 2))
would return c(1, 2, 4, 5, 7, 8, 10). Now, this is possible to do this with e.g. seq(1, 10, by = 1)[c(T, T, F)] because it's a simple case, but is there a way to make it generalizable to more complex sequences?
Some examples
seq(1, 100, by = 1:5)
#[1] 1 2 4 7 11 16 17 19 22 26 31...
seq(8, -5, by = c(3, 8))
#[1] 8 5 -3
This doesn't seem possible Maël. I suppose it's easy enough to write one?
seq2 <- function(from, to, by) {
vals <- c(0, cumsum(rep(by, abs(ceiling((to - from) / sum(by))))))
if(from > to) return((from - vals)[(from - vals) >= to])
else (from + vals)[(from + vals) <= to]
}
Testing:
seq2(1, 10, by = c(1, 2))
#> [1] 1 2 4 5 7 8 10
seq2(1, 100, by = 1:5)
#> [1] 1 2 4 7 11 16 17 19 22 26 31 32 34 37 41 46 47 49 52 56 61 62 64 67 71
#> [26] 76 77 79 82 86 91 92 94 97
seq2(8, -5, by = c(3, 8))
#> [1] 8 5 -3
Created on 2022-12-23 with reprex v2.0.2