[R] merge some columns

[Dennis Murphy]

Hi:

Here's one approach:

d <- read.table(textConnection("
V1 V2 V3 V4 V5 V6
1  G  A  G  G  G  G
2  A  A  G  A  A  G"), header = TRUE, stringsAsFactors = FALSE)
closeAllConnections()

# Create two vectors of variable names, one for odd numbered,
# one for even numbered
vars1 <- names(d)[seq_along(names(d)) %% 2 == 1]
vars2 <- names(d)[seq_along(names(d)) %% 2 == 0]

# Apply the paste sequentially to corresponding pairs
# in vars1 and vars2; get() is used to get the data associated
# with the variable names in vars1 and vars2
d2 <- sapply(seq_along(vars1),
         function(j) with(d, paste(get(vars1[j]), get(vars2[j]), sep = '/')))

# Convert to data frame:
d2 <- as.data.frame(d2, stringsAsFactors = FALSE)
str(d2)

HTH,
Dennis

On Fri, Sep 2, 2011 at 5:34 AM, Joao Fadista <Joao.Fadista at med.lu.se> wrote:
> Dear all,
>
> I would like to know how to merge columns like:
>
> Input file:
>  V1 V2 V3 V4 V5 V6
> 1  G  A  G  G  G  G
> 2  A  A  G  A  A  G
>
> Desired output file:
>    V1  V2   V3
> 1  G/A G/G G/G
> 2  A/A G/A A/G
>
> So for every 2 consecutive columns merge their content into one.
> Thanks in advance.
>
>
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>
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