Let's start with something simple and relatively easy to understand,
since you're new to this.
First, here's an example of the core of the idea:
paste('a',1:4)
[1] "a 1" "a 2" "a 3" "a 4"
Make it a little closer to your situation:
paste('a*',1:4, sep='')
[1] "a*1" "a*2" "a*3" "a*4"
Sometimes it helps to save the number of rows in your dataframe in a
new variable
nr <- nrow(df)
Then, for your first column, the "a*" in the above example is df$V1[1]
For the 1:4 in the example, you use df$V1[ 2:nr]
Put it together and you have:
dfnew <- df
dfnew$V1[ 2:nr] <- paste( dfnew$V1[1], dfnew$V1[ 2:nr] )
But you can use "-1" instead of "2:nr", and you get
dfnew$V1[ -1 ] <- paste( dfnew$V1[1], dfnew$V1[ -1] )
That's how you can do it one column at a time.
Since you have only four columns, just do the same thing to V2, V3, and V4.
But if you want a more general method, one that works no matter how
many columns you have, and no matter what they are named, then you
can use lapply() to loop over the columns. This is what Patrick
Connolly suggested, which is
as.data.frame(lapply(df, function(x) paste(x[1], x[-1], sep = "")))
Note, though, that this will do it to all columns, so if you ever
happen to have a dataframe where you don't want to do all columns,
you'll have to be a little trickier with the lapply() solution.
-Don
At 6:48 PM -0700 8/11/09, Jill Hollenbach wrote:
Hi,
I am trying to edit a data frame such that the string in the first line is
appended onto the beginning of each element in the subsequent rows. The data
looks like this:
df
V1 V2 V3 V4
1 DPA1* DPA1* DPB1* DPB1*
2 0103 0104 0401 0601
3 0103 0103 0301 0402
.
.
and what I want is this:
dfnew
V1 V2 V3 V4
1 DPA1* DPA1* DPB1* DPB1*
2 DPA1*0103 DPA1*0104 DPB1*0401 DPB1*0601
3 DPA1*0103 DPA1*0103 DPB1*0301 DPB1*0402
any help is much appreciated, I am new to this and struggling.
Jill
___
Jill Hollenbach, PhD, MPH
Assistant Staff Scientist
Center for Genetics
Children's Hospital Oakland Research Institute
jhollenb...@chori.org
--
View this message in context:
http://*www.*nabble.com/paste-first-row-string-onto-every-string-in-column-tp24928720p24928720.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@r-project.org mailing list
https://*stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://*www.*R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
