CODEWITHSUNDEEP
rsequence
Quinn
Quinn

Reputation: 429

Move value along a sequence

I am aiming to produce a sequence something like this:

> c(1, rep(9, 7))
[1] 1 9 9 9 9 9 9 9
> c(9, 1, rep(9, 6))
[1] 9 1 9 9 9 9 9 9
> c(rep(9, 2), 1, rep(9, 5))
[1] 9 9 1 9 9 9 9 9

In essence, I have a sequence that stays constant, but I want to move a value along, one space at a time.

Obviously I could write this out in a way similar to what I have done, but my real sequence is much larger so this isn't that practical. My search for this has been somewhat futile so any advice would be appreciated. Thanks

Upvotes: 2

Views: 72

Answers (4)

Sandipan Dey
Sandipan Dey

Reputation: 23101

Yet another way to get the same result:

x <- c(1, rep(9, 7))
sapply(8:1, function(n)c(tail(x,-n),head(x,n)))

    [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
[1,]    1    9    9    9    9    9    9    9
[2,]    9    1    9    9    9    9    9    9
[3,]    9    9    1    9    9    9    9    9
[4,]    9    9    9    1    9    9    9    9
[5,]    9    9    9    9    1    9    9    9
[6,]    9    9    9    9    9    1    9    9
[7,]    9    9    9    9    9    9    1    9
[8,]    9    9    9    9    9    9    9    1

Upvotes: 1

Sotos
Sotos

Reputation: 51582

You can create a matrix and replace the diagonal, i.e.

m1 <-matrix(data = 9, nrow = 8, ncol = 8)
diag(m1) <- 1
m1

#     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
#[1,]    1    9    9    9    9    9    9    9
#[2,]    9    1    9    9    9    9    9    9
#[3,]    9    9    1    9    9    9    9    9
#[4,]    9    9    9    1    9    9    9    9
#[5,]    9    9    9    9    1    9    9    9
#[6,]    9    9    9    9    9    1    9    9
#[7,]    9    9    9    9    9    9    1    9
#[8,]    9    9    9    9    9    9    9    1

A one liner for that would be:

`diag<-`(matrix(data = 9, nrow = 8, ncol = 8),1)

Upvotes: 4

Roland
Roland

Reputation: 132576

You can use stats::filter:

x <- c(1, rep(9, 7))

for (i in 1:8) print(x <- c(filter(x, c(0, 1), circular = TRUE, sides = 1)))
#[1] 9 1 9 9 9 9 9 9
#[1] 9 9 1 9 9 9 9 9
#[1] 9 9 9 1 9 9 9 9
#[1] 9 9 9 9 1 9 9 9
#[1] 9 9 9 9 9 1 9 9
#[1] 9 9 9 9 9 9 1 9
#[1] 9 9 9 9 9 9 9 1
#[1] 1 9 9 9 9 9 9 9

Obviously, this moves all values along and might not be what you are looking for if you have more than two different values in the sequence. Your question is a bit unclear.

Upvotes: 2

akrun
akrun

Reputation: 886938

An option is embed

 embed(c(rev(v1),rev(v1)), length(v1))
 #      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
 #[1,]    1    9    9    9    9    9    9    9
 #[2,]    9    1    9    9    9    9    9    9
 #[3,]    9    9    1    9    9    9    9    9
 #[4,]    9    9    9    1    9    9    9    9
 #[5,]    9    9    9    9    1    9    9    9
 #[6,]    9    9    9    9    9    1    9    9
 #[7,]    9    9    9    9    9    9    1    9
 #[8,]    9    9    9    9    9    9    9    1
 #[9,]    1    9    9    9    9    9    9    9


embed(c(rev(v2),rev(v2)), length(v2))
#      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
# [1,]    1    5    5    5    3    2    5    7
# [2,]    7    1    5    5    5    3    2    5
# [3,]    5    7    1    5    5    5    3    2
# [4,]    2    5    7    1    5    5    5    3
# [5,]    3    2    5    7    1    5    5    5
# [6,]    5    3    2    5    7    1    5    5
# [7,]    5    5    3    2    5    7    1    5
# [8,]    5    5    5    3    2    5    7    1
# [9,]    1    5    5    5    3    2    5    7

data

v1 <- c(1, 9, 9, 9, 9, 9, 9, 9)
v2 <- c(1, 5, 5, 5, 3, 2, 5, 7)

Upvotes: 1

Related Questions