Split thousands of columns at a time by '/' on multiple lines, sort the values in the new rows and add 'NA' values

Question

I would like to split a data frame with thousands of columns. The data frame looks like this:

# sample data of four columns
sample <-read.table(stdin(),header         


        

Answer 1

Here's an alternative solution that instead of generating multiple rows, generates a bit mask for each value indicating presence or absence of the "0" "1" "2" etc bit.

> sample <-read.table(stdin(),header=TRUE,sep="",
                          row.names=1,colClasses="character")
0: POS v1  v2  v3  v4
1: 152 0   0/1 0/2 0/1/2
2: 73  1   0   0/1 0/1
3: 185 0   1   0/3 0
4: 
> # transform the strings into bit masks
> B<-function(X)lapply(strsplit(X,"/"),
                function(n)Reduce(bitOr,bitwShiftL(1,as.numeric(n)),0))
> B("0/1")
[[1]]
[1] 3
> # apply it everywhere
> s<-colwise(B)(sample)
> rownames(s)<-rownames(sample)
> s
    v1 v2 v3 v4
152  1  3  5  7
73   2  1  3  3
185  1  2  9  1

While it's not what you asked for, assuming the set of enum values is small (0,1,2) it is much much more efficient in storage space and can be processed easily:

Which elements have v1 "0" and v3 "0" and "1"

> subset(s, bitAnd(v1,B("0")) & bitAnd(v4,B("0/1")))
    v1 v2 v3 v4
152  1  3  5  7
185  1  2  9  1