Danny Danny - 1 month ago 5
R Question

Saving instructional results in R as a matrix or object

In the package CoinMinD I ran the GM function on the following code:

GM(c(2,4,5,1),0.05)


The results are as follows:

Original Intervals
Lower Limit
[1] 0.03470190 0.10880765 0.15542939 0.01035233
Upper Limit
[1] 0.5266663 0.6718765 0.7349127 0.4413580
Adjusted Intervals
Lower Limit
[1] 0.03470190 0.10880765 0.15542939 0.01035233
Upper Limit
[1] 0.5266663 0.6718765 0.7349127 0.4413580
Volume
[1] 0.06918613


I am trying to create a matrix where the first two lines Lower Limit and the Upper Limit, appear as follows:

[,1] [,2]
[1,] 0.03470190 0.5266663
[2,] 0.10880765 0.6718765
[3,] 0.15542939 0.7349127
[4,] 0.01035233 0.4413580


Unforunately, when I save the code to an object:

c<-GM(c(2,4,5,1),0.05)


and run

c[1]


or

GM(c(2,4,5,1),0.05) [1]


I only get the last line of the results:

> c[1]
[1] 0.06918613

Answer

Interesting question! Luckily the function GM is not a long one so we can look inside:

function (inpmat, alpha) 
{
    ## ... those lines for computing results are left out...
    cat("Original Intervals\n")
    cat("Lower Limit\n")
    print(GM.LL)
    cat("Upper Limit\n")
    print(GM.UL)
    cat("Adjusted Intervals\n")
    cat("Lower Limit\n")
    print(LLA)
    cat("Upper Limit\n")
    print(ULA)
    cat("Volume\n")
    print(VOL)
}

All values you want to extract are only printed rather than exported. We can easily modify this function to export them.

myGM <- function (inpmat, alpha) 
{
    k = length(inpmat)
    s = sum(inpmat)
    chi = qchisq(1 - (alpha/k), df = 1)
    pi = inpmat/s
    GM.UL = (chi + 2 * inpmat + sqrt(chi * chi + 4 * inpmat * 
        chi * (1 - pi)))/(2 * (chi + s))
    GM.LL = (chi + 2 * inpmat - sqrt(chi * chi + 4 * inpmat * 
        chi * (1 - pi)))/(2 * (chi + s))
    LLA = 0
    ULA = 0
    for (r in 1:length(inpmat)) {
        if (GM.LL[r] < 0) 
            LLA[r] = 0
        else LLA[r] = GM.LL[r]
        if (GM.UL[r] > 1) 
            ULA[r] = 1
        else ULA[r] = GM.UL[r]
    }
    diA = ULA - LLA
    VOL = round(prod(diA), 8)
    ## the lines for printing are removed
    ## replace it with the line below
    list(limit = matrix(c(GM.LL, GM.UL, LLA, ULA), ncol = 4L,
                        dimnames = list(NULL, c("ori_low", "ori_up", "adj_low", "adj_up"))),
         volume = VOL)
}

## test
myGM(c(2,4,5,1),0.05)

#$limit
#        ori_low    ori_up    adj_low    adj_up
#[1,] 0.03470190 0.5266663 0.03470190 0.5266663
#[2,] 0.10880765 0.6718765 0.10880765 0.6718765
#[3,] 0.15542939 0.7349127 0.15542939 0.7349127
#[4,] 0.01035233 0.4413580 0.01035233 0.4413580
#
#$volume
#[1] 0.06918613

You can easily extract the column you want from $limit.

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