[R] divide column in a dataframe based on a character

[Bill.Venables at csiro.au]

You are nearly there.
____

example(data.frame)
zz <- c("aa_bb","bb_cc","cc_dd","dd_ee","ee_ff",
	   "ff_gg","gg_hh","ii_jj","jj_kk","kk_ll")
ddd <- cbind(dd, group = zz)

ddd <- within(ddd, {
	group <- as.character(group)
	tmp <- do.call(rbind, strsplit(group, "_"))
	group_b <- tmp[,2]
	group_a <- tmp[,1]
	rm(tmp, group)
})

____

> ddd
   x  y fac char group_a group_b
1  1  1   B    a      aa      bb
2  1  2   B    b      bb      cc
3  1  3   A    c      cc      dd
4  1  4   A    d      dd      ee
5  1  5   A    e      ee      ff
6  1  6   C    f      ff      gg
7  1  7   A    g      gg      hh
8  1  8   B    h      ii      jj
9  1  9   C    i      jj      kk
10 1 10   B    j      kk      ll

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Daisy Englert Duursma
Sent: Tuesday, 26 October 2010 1:57 PM
To: r-help at r-project.org
Subject: [R] divide column in a dataframe based on a character

Hello,

If I have a dataframe:

example(data.frame)
zz<-c("aa_bb","bb_cc","cc_dd","dd_ee","ee_ff","ff_gg","gg_hh","ii_jj","jj_kk","kk_ll")
ddd <- cbind(dd, group = zz)

and I want to divide the column named group by the "_", how would I do this?

so instead of the first row being
 x   y  fac char  group
 1  1   C    a     aa_bb

it should be:
 x  y fac  char group_a    group_b
 1  1   C    a      aa             bb



I know for a vector I can:
x1 <- c("a_b","b_c","c_d")
do.call("rbind",strsplit(x1, "_"))

but I am not sure how this relates to my data.frame

Thanks,
Daisy


-- 
Daisy Englert Duursma

Room E8C156
Dept. Biological Sciences
Macquarie University  NSW  2109
Australia

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