Generate sequence with alternating increments in R? [duplicate]

Answer 1

rep(seq(0,990,by=10), each=8) + seq(1,8)

Answer 2

You want to exclude numbers that are 0 or 9 (mod 10). So you can try this too:

n <- 1000 # upper bound
x <- 1:n
x <- x[! (x %% 10) %in% c(0,9)] # filter out (0, 9) mod (10)

head(x,80)
# [1]  1  2  3  4  5  6  7  8 11 12 13 14 15 16 17 18 21 22 23 24 25 26 27  
# 28 31 32 33 34 35 36 37 38 41 42 43 44 45 46 47 48 51 52 53 54 55 56 57
# 58 61 62 63 64 65 66 67 68 71 72 73 74 75 76 77 78 81 82 83 84 85 
# 86 87 88 91 92 93 94 95 96 97 98

Or in a single line using Filter:

Filter(function(x) !((x %% 10) %in% c(0,9)), 1:100)
# [1]  1  2  3  4  5  6  7  8 11 12 13 14 15 16 17 18 21 22 23 24 25 26 27 28 31 32 33 34 35 36 37 38 41 42 43 44 45 46 47 48 51 52 53 54 55 56 57
# [48] 58 61 62 63 64 65 66 67 68 71 72 73 74 75 76 77 78 81 82 83 84 85 86 87 88 91 92 93 94 95 96 97 98

Answer 3

With a cycle: for(value in c(seq(1,991,10))){vector <- c(vector,seq(value,value+7))}

Answer 4

This is a perfect case of vectorisation( recycling too) in R. read about them

(1:100)[rep(c(TRUE,FALSE), c(8,2))]
# [1]  1  2  3  4  5  6  7  8 11 12 13 14 15 16 17 18 21 22 23 24 25 26 27 28 31 32
#[27] 33 34 35 36 37 38 41 42 43 44 45 46 47 48 51 52 53 54 55 56 57 58 61 62 63 64
#[53] 65 66 67 68 71 72 73 74 75 76 77 78 81 82 83 84 85 86 87 88 91 92 93 94 95 96
#[79] 97 98