I want to split a parent sub-vectors such that these conditions hold:

1. Each sub-vector has equal and constant length l.
2. The sub-vectors overlap on one another with l -1
3. Number of sub-vector is given as length(ts) - l 2
4. The last sub-vector should include the first element of the parent vector as its last sub-element.

.

ts <- 1:11 # the parent vector
l <- 7 # constant length of sub-vectors to be
m <- length(ts) - l   1 # number of sub-vector to be
split(t(embed(ts, m))[m:1,], 1:m) 

When I tried this (with m <- length(ts) - l 1) I got my l = 7 like I want but m = 5 instead of m = 6 like I want.

#$`1`
#[1] 1 2 3 4 5 6 7

#$`2`
#[1] 2 3 4 5 6 7 8

#$`3`
#[1] 3 4 5 6 7 8 9

#$`4`
#[1]  4  5  6  7  8  9 10

#$`5`
#[1]  5  6  7  8  9 10 11

When I tried this (with m <- length(ts) - l 2) I got m = 6 like I want but l = 6 instead of l = 7.

ts <- 1:11 # the parent vector
l <- 7 # constant length of sub-vectors to be
m <- length(ts) - l   2 # number of sub-vector to be
split(t(embed(ts, m))[m:1,], 1:m) 

This is what I got

#$`1`
#[1] 1 2 3 4 5 6

#$`2`
#[1] 2 3 4 5 6 7

#$`3`
#[1] 3 4 5 6 7 8

#$`4`
#[1] 4 5 6 7 8 9

#$`5`
#[1]  5  6  7  8  9 10

#$`6`
#[1]  6  7  8  9 10 11

What I Want

#$`1`
#[1] 1 2 3 4 5 6 7

#$`2`
#[1] 2 3 4 5 6 7 8

#$`3`
#[1] 3 4 5 6 7 8 9

#$`4`
#[1]  4  5  6  7  8  9 10

#$`5`
#[1]  5  6  7  8  9 10 11

#$`6`
#[1]  6  7  8  9 10 11  1

CodePudding user response：

If it only has to work for parent vectors that contain sequences of integers from 1 (like 1:10, 1:8) then this should do:

ts <- 1:11
l <- 7
m <- length(ts) - l   2


lapply(1:m, function(x) {
  y <- x:(x l-1)
  y <- ifelse(y>max(ts), y-max(ts), y)} #here you make sure that 12 becomes 1 etc.
       )

But if you want this to work for any type of atomic vector (e.g. the letters A, B, C...K) , do this:

ts2 <- LETTERS[1:11]
l <- 7
m <- length(ts) - l   2

# the output from the code above is stored to be used as index
idx <- lapply(1:m, function(x) {
  y <- x:(x l-1)
  y <- ifelse(y>length(ts2), y-length(ts2), y)}
)

# apply index to the parent vector
lapply(idx, function(x) ts2[x])

CodePudding user response：

I would use filter:

ts <- 1:11 
l <- 7

lapply(seq_len(length(ts) - l   2), function(i) {
  p <- rep(0, l)
  p[i] <- 1
  res <- c(stats::filter(rev(ts), filter = p, 
                         circular = TRUE, sides = 1))
  rev(res)[seq_len(l)]
})
#[[1]]
#[1] 1 2 3 4 5 6 7
#
#[[2]]
#[1] 2 3 4 5 6 7 8
#
#[[3]]
#[1] 3 4 5 6 7 8 9
#
#[[4]]
#[1]  4  5  6  7  8  9 10
#
#[[5]]
#[1]  5  6  7  8  9 10 11
#
#[[6]]
#[1]  6  7  8  9 10 11  1

CodePudding user response：

Fill a matrix with appropriate dimensions, index, and split

asplit(
  matrix(ts, nrow = length(ts)   1, ncol = length(ts) - l   1)[1:(l   1), ],
  MARGIN = 2)

#[[1]]
#[1] 1 2 3 4 5 6 7
#
#[[2]]
#[1] 2 3 4 5 6 7 8
#
#[[3]]
#[1] 3 4 5 6 7 8 9
#
#[[4]]
#[1]  4  5  6  7  8  9 10
#
#[[5]]
#[1]  5  6  7  8  9 10 11
#
#[[6]]
#[1]  6  7  8  9 10 11  1

CodePudding user response：

Here you go:

ts <- 1:11 # the parent vector
l <- 7 # constant length of sub-vectors to be
m <- length(ts) - l   2 # number of sub-vector to be

library(magrittr)
lapply(1:m, function(i){
  c(0, rep(ts, 4)) %>% # Adding leading zero (cut in first iter; repeat a few times to not run out if we increase m
    tail(-i) %>% # Cut first i elements (including added zero)
    head(l) # Retain first l of the remaining part
})