CODEWITHSUNDEEP
r
Camford Oxbridge
Camford Oxbridge

Reputation: 894

How to insert elements in a vector at regular intervals in R

Is there any alternative method of R for the problem explained here: How to insert elements in a vector at regular intervals in Matlab

Namely, from a vector x <- c(1,2,3,4,5,6,7,8,9,10,11,12), I want to obtain a vector y given by

y     <- c(0, 1, 2, 3,
           0, 4, 5, 6,
           0, 7, 8, 9,
           0,10,11,12)

... I found the following page,... maybe duplicate

R: insert elements into vector (a variation)

Edit I slighly modified the answer of @jay.sf . I think his interval.length is not our intuitive interval length.

    x <- 1:16
    interval.length <- 2
    co_interval.length <- length(x)/interval.length
    as.vector(t(cbind(0, matrix(x, co_interval.length, byrow=T))))

[1]  0  1  2  0  3  4  0  5  6  0  7  8  0  9 10  0 11 12  0 13 14  0 15 16

Upvotes: 2

Views: 287

Answers (2)

Allan Cameron
Allan Cameron

Reputation: 173793

Another way is to make use of arithmetical indexing:

y <- numeric(16)
y[x + 1 + (x - 1) %/% 3] <- x
y
#> [1]  0  1  2  3  0  4  5  6  0  7  8  9  0 10 11 12

Upvotes: 2

jay.sf
jay.sf

Reputation: 72593

You could make a matrix and coerce it into a vector.

interval.length <- 4
as.vector(t(cbind(0, matrix(x, interval.length, byrow=T))))
# [1]  0  1  2  3  0  4  5  6  0  7  8  9  0 10 11 12

Upvotes: 4

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