[R] function using values separated by a comma

[Gabor Grothendieck]

On Fri, Oct 8, 2010 at 1:19 AM, burgundy <sauburn at yahoo.com> wrote:
>
> Hello,
>
> I have a dataframe (tab separated file) which looks like the example below -
> two values separated by a comma, and tab separation between each of these.
>
>     [,1]  [,2]  [,3]  [ ,4]
> [1,] 0,1  1,3   40,10  0,0
> [2,] 20,5  4,2  10,40  10,0
> [3,] 0,11  1,2  120,10  0,0
>
> I would like to calculate the percentage of the smallest number separated by
> the comma by:
> 1) summing the values e.g. for [1,3] where 40,10, 40+10 = 50
> 2) taking the first value and dividing it by the total e.g. for [1,3], 40/50
> = 0.8
> 3) where the value generated by 2) is >0.5, print 1-value, otherwise, leave
> value e.g. for [1,3], where value is 0.8, print 1-0.8 = 0.2
>
> plan to generate file like:
>
>    [,1]  [,2]  [,3]  [,4]
> [1,] 1   0.25  0.2  0
> [2,] 0.2  0.33  0.2  1
> [3,] 1  0.33  0.08  0

Try using gsubfn in gsubfn (http://gsubfn.googlecode.com).  Using that
match a regular expression consisting of digits, a comma and digits
capturing the two strings of digits and passing them to function f
replacing the expression with the output of f.  Then read the
resulting text into a data frame.

library(gsubfn)
L <- c(" 0,1  1,3   40,10  0,0", " 20,5  4,2  10,40  10,0",
   " 0,11  1,2  120,10  0,0")

f <- function(a, b) { x <- as.numeric(c(a, b)); min(x)/sum(x) }
L2 <- gsubfn("(\\d+),(\\d+)", f, L)

DF <- read.table(textConnection(L2))

which gives:

> DF
   V1        V2         V3  V4
1 0.0 0.2500000 0.20000000 NaN
2 0.2 0.3333333 0.20000000   0
3 0.0 0.3333333 0.07692308 NaN

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