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How to find the difference between a value and its cabinet value in a vector in R?

I have a vector as shown below:

x= c(1,23,4,15,8,17,21)

after the sorting values ​​in the vector we have:

 c(1,4,8,15,17,21,23)

my required result:

 c(3, 3, 4, 2, 2, 2, 2)

Which contains the difference between a value and its closest value.

But if I want to have an output without sorting, is there any solution? I need c (3,2,3,2,4,2,2) to find out which sample has the highest value in the output table (here the fifth value is the result)

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5 answers
 d <- diff(sort(x)) pmin(c(d, NA), c(NA, d), na.rm = TRUE) # [1] 3 3 4 2 2 2 2
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If you understand correctly, you want to calculate the smallest value between a member of a vector and its neighbors.

First we sort the data.

 x= sort(c(1,23,4,15,8,17,21))

Then we calculate the difference with the left neighbor (which is missing for item 1) and the difference with the right neighbor (which is missing for item 2)

 diffs <- cbind(c(NA,diff(x)),c(diff(x),NA))

So, now we have a difference with left and right for each element, now all that remains is to find the smallest:

 res <- apply(diffs,MARGIN=1, min, na.rm=T)

Note that although this solution contains an explanation, the other solutions provided (in particular the pmin approach by @Julius) are probably faster when performance is a problem.

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Good decisions. Julius' seems the fastest:

 library(microbenchmark) set.seed(1262016) x <- sample(1e5) all.equal(heroka, NicE, julius, Ambler) [1] TRUE microbenchmark( julius = {d <- diff(sort(x)) pmin(c(d, NA), c(NA, d), na.rm = TRUE)}, NicE = {x <- sort(x) pmin(abs(x-lag(x)),abs(x-lead(x)),na.rm=T)}, Heroka = {x= sort(x) diffs <- cbind(c(NA,diff(x)),c(diff(x),NA)) apply(diffs,MARGIN=1, min, na.rm=T)}, Ambler = {n <- length(x) ds <- c( x[2] - x[1], sapply( 2:(n - 1), function(i) min(x[i] - x[i - 1], x[i + 1] - x[i]) ), x[n] - x[n - 1] )} ) # Unit: milliseconds # expr min lq mean median uq max neval # julius 4.167302 5.066164 13.94478 7.967066 10.11920 89.06298 100 # NicE 4.678274 6.804918 13.85149 9.297575 12.45606 83.41032 100 # Heroka 142.107887 176.768431 199.96590 196.269671 221.05851 299.30336 100 # Ambler 268.724129 309.238792 334.66432 329.252146 359.88103 409.38698 100
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You can try:

 library(dplyr) x <- sort(x) pmin(abs(x-lag(x)),abs(x-lead(x)),na.rm=T) #[1] 3 3 4 2 2 2 2

x-lag(x) calculates the difference with the nearest lower number, x-lead(x) difference with the nearest lower number.

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You can just do it with brute force:

 x <- c(1, 4, 8, 15, 17, 21, 23) n <- length(x) ds <- c( x[2] - x[1], sapply( 2:(n - 1), function(i) min(x[i] - x[i - 1], x[i + 1] - x[i]) ), x[n] - x[n - 1] )
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