On Wed, 4 Aug 2010, David Winsemius wrote:
> Dear list;
>
> I just created a utility function that replicates what I have done in the
> past with Excel or OO.org by putting a formula of the form =sum($A1:A$1) in
> an upper-corner of a section and then doing a "fill" procedure by
dragging
> the lower-rt corner down and to the right. When divided by the grand sum of
> the entries this function then calculates a 2D-discrete-ECDF.
>
> I keep thinking I am missing the obvious, but I did try searching. Here is
my
> effort at creating that functionality:
>
> ecdf.tbl <- function (.dat) { .dat <- data.matrix(.dat) #speeds up
> calculations
> .sdat <- matrix(0, nrow(.dat), ncol(.dat) )
> .sdat[] <- sapply(1:ncol(.dat), function(x)
> sapply(1:nrow(.dat),
> function(y) sum(.dat[1:y, 1:x], na.rm=TRUE ) )
> )
> return(.sdat) }
>
ecdf.tbl2 <-
function(mat) {
mat[is.na(mat)] <- 0
t( apply( apply( mat,2, cumsum ), 1, cumsum ))}
HTH,
Chuck
>> tst <- read.table(textConnection("NA 5 6
> 4 5 7
> 5 6 8
> 6 7 9
> NA 8 NA") )
>
>> tst
> V1 V2 V3
> 1 NA 5 6
> 2 4 5 7
> 3 5 6 8
> 4 6 7 9
> 5 NA 8 NA
>
>> ecdf.tbl(tst)
> [,1] [,2] [,3]
> [1,] 0 5 11
> [2,] 4 14 27
> [3,] 9 25 46
> [4,] 15 38 68
> [5,] 15 46 76
>
>> ecdf.tbl(tst)/sum(tst, na.rm=TRUE)
> [,1] [,2] [,3]
> [1,] 0.00000000 0.06578947 0.1447368
> [2,] 0.05263158 0.18421053 0.3552632
> [3,] 0.11842105 0.32894737 0.6052632
> [4,] 0.19736842 0.50000000 0.8947368
> [5,] 0.19736842 0.60526316 1.0000000
>
>
> Did I miss a more compact vectorized or sweep()-ed solution? (I realize
this
> is not really a function in the sense that ecdf() is.) I have seen
prop.table
> and margin.table, but could not see how they would address this problem.
>
> --
>
> David Winsemius, MD
> West Hartford, CT
>
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> and provide commented, minimal, self-contained, reproducible code.
>
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901