CODEWITHSUNDEEP
rrstudioknapsack-problem
Interrobang
Interrobang

Reputation: 127

R mknapsack function

I run the R program from article where used mknapsack function from adagio package, and everything's good. But if I want using a random values I get an error "Error condition raised".

I have a program:

n=16
m=5
max=700
min = 10

planks_we_have = floor(runif(n=m, min = 100, max = max))
planks_we_want = floor(runif(n=n, min = min, max = 16))

library(adagio)
# mknapsack calling signature is: mknapsack(values, weights, capacities)
solution <- mknapsack(planks_we_want, planks_we_want, planks_we_have)
# Above I added +1 cm  to each length to compensate for the loss when sawing.
solution$ksack
# Now pretty printing what to cut so that we don't make mistakes...
assignment <- data.frame(cut_this = planks_we_have[solution$ksack], into_this = planks_we_want)
t(assignment[order(assignment[,1]), ])

Result:

Warning
In mknapsack(planks_we_want, planks_we_want, planks_we_have) :
  Error condition raised: check input data ...!

Error
In data.frame(cut_this = planks_we_have[solution$ksack], into_this = planks_we_want) :
  Arguments imply different numbers of lines: 0, 5

I don't understand what is the reason. The source code of the knapsack function gives me nothing:

function (p, w, k, bck = -1) 
{
    stopifnot(is.numeric(p), is.numeric(w), is.numeric(k))
    if (any(w <= 0)) 
        stop("'weights' must be a vector of positive numbers.")
    if (any(p <= 0)) 
        stop("'profits' must be a vector of positive numbers.")
    if (any(floor(p) != ceiling(p)) || any(floor(w) != ceiling(w)) || 
        any(floor(k) != ceiling(k)) || any(p >= 2^31) || any(w >= 
        2^31) || any(k >= 2^31)) 
        stop("All inputs must be positive integers < 2^31 !")
    n <- length(p)
    m <- length(k)
    if (length(w) != n) 
        stop("Profit 'p' and weight 'w' must be vectors of equal length.")
    xstar <- vector("integer", n)
    vstar <- 0
    num <- 5 * m + 14 * n + 4 * m * n + 3
    wk <- numeric(n)
    iwk <- vector("integer", num)
    S <- .Fortran("mkp", as.integer(n), as.integer(m), as.integer(p), 
        as.integer(w), as.integer(k), bs = as.integer(bck), 
        xs = as.integer(xstar), vs = as.integer(vstar), as.numeric(wk), 
        as.integer(iwk), as.integer(num), PACKAGE = "adagio")
    if (S$vs < 0) 
        warning("Error condition raised: check input data ...!")
    return(list(ksack = S$xs, value = S$vs, btracks = S$bs))
}

Versions:

R - 3.4.1
Adagio - 0.7.1

Upvotes: 1

Views: 205

Answers (1)

Hans W.
Hans W.

Reputation: 1829

Please read first the help page if you have problems with a function. Looking at the solution returned, it has error code vs=-7 and help says "vs=-7 if array k is not correctly sorted". Sorting the vector of capacities may give another error, for instance in case all items can be put in one knapsack. Of course, all this depends on the random numbers generated (better fix random numbers before asking).

Upvotes: 1

Related Questions