R - Generate a sequence of numbers

Question

I am trying to create sequences of number of 6 cases, but with 144 cases intervals.

Like this one for example

c(1:6, 144:149, 288:293)  1   2   3   4   5   6 144 145 146 147 148 149 288 289 290 291 292 293 

How could I generate automatically such a sequence with

seq  

or with another function ?

Answer 1

I find the sequence function to be helpful in this case. If you had your data in a structure like this:

(info <- data.frame(start=c(1, 144, 288), len=c(6, 6, 6))) #   start len # 1     1   6 # 2   144   6 # 3   288   6 

then you could do this in one line with:

sequence(info$len) + rep(info$start-1, info$len) #  [1]   1   2   3   4   5   6 144 145 146 147 148 149 288 289 290 291 292 293 

Note that this solution works even if the sequences you're combining are different lengths.

Answer 2

Here's one approach:

unlist(lapply(c(0L,(1:2)*144L-1L),`+`,seq_len(6))) # or... unlist(lapply(c(1L,(1:2)*144L),function(x)seq(x,x+5))) 

Here's a way I like a little better:

rep(c(0L,(1:2)*144L-1L),each=6) + seq_len(6) 

Generalizing...

rlen  <- 6L rgap  <- 144L rnum  <- 3L  starters <- c(0L,seq_len(rnum-1L)*rgap-1L)  rep(starters, each=rlen) + seq_len(rlen) # or... unlist(lapply(starters+1L,function(x)seq(x,x+rlen-1L)))