R help - May 2010 - splitting character strings and converting to numeric vectors

This seemingly should be quite simple but I can't solve it:

I have a long character vector of geographic data (data frame column named
"XY") whose elements vary in length (from 11 to 14 chars).  Each
element is
structured as a set of digits, then an underscore, then more digits, e.g:
> data.frame(head(as.character(XY)))
  head.as.character.XY..
1         -448623_854854
2         -448563_854850
3         -448442_854842
4         -448301_854833
5         -448060_854818
6         -446828_854736

I simply need to separate the two sets of digits from each other and assign
them into new columns.  The closest I've been able to get is by:
> test=t(as.matrix(data.frame(head(strsplit(as.character(XY),
"\\_")))))
> test
                       [,1]      [,2]    
c...448623....854854.. "-448623" "854854"
c...448563....854850.. "-448563" "854850"
c...448442....854842.. "-448442" "854842"
c...448301....854833.. "-448301" "854833"
c...448060....854818.. "-448060" "854818"
c...446828....854736.. "-446828" "854736"

So far so good, but  columns 1:2 will not coerce to either numeric or
integer, for unknown reasons.  Thanks for any help (and/or suggestions on a
better way to code this).



Jim Bouldin, PhD
Research Ecologist
Department of Plant Sciences, UC Davis
Davis CA, 95616
530-554-1740

Hi

Probably not the best way
> read.table("clipboard", header=T)
  head.as.character.XY..
1         -448623_854854
2         -448563_854850
3         -448442_854842
4         -448301_854833
5         -448060_854818
6         -446828_854736
> test=read.table("clipboard", header=T)
now do the split
> ls<-strsplit(as.character(test[,1]), "_")
> ls
[[1]]
[1] "-448623" "854854" 

[[2]]
[1] "-448563" "854850" 

and change list to numeric

t(sapply(ls, as.numeric))
        [,1]   [,2]
[1,] -448623 854854
[2,] -448563 854850
[3,] -448442 854842
[4,] -448301 854833
[5,] -448060 854818
[6,] -446828 854736

Result is numeric matrix. You probably could start directly from your XY 
object, but it depends what it is. And maybe you could read it the way 
Gabor recently post with

read.table(...., sep= "_", ....)

Regards
Petr

r-help-bounces at r-project.org napsal dne 06.05.2010 14:12:40:
> 
> This seemingly should be quite simple but I can't solve it:
> 
> I have a long character vector of geographic data (data frame column 
named
> "XY") whose elements vary in length (from 11 to 14 chars).  Each
element
is
> structured as a set of digits, then an underscore, then more digits, 
e.g:
> 
> > data.frame(head(as.character(XY)))
>   head.as.character.XY..
> 1         -448623_854854
> 2         -448563_854850
> 3         -448442_854842
> 4         -448301_854833
> 5         -448060_854818
> 6         -446828_854736
> 
> I simply need to separate the two sets of digits from each other and 
assign
> them into new columns.  The closest I've been able to get is by:
> 
> > test=t(as.matrix(data.frame(head(strsplit(as.character(XY),
"\\_")))))
> > test
>                        [,1]      [,2] 
> c...448623....854854.. "-448623" "854854"
> c...448563....854850.. "-448563" "854850"
> c...448442....854842.. "-448442" "854842"
> c...448301....854833.. "-448301" "854833"
> c...448060....854818.. "-448060" "854818"
> c...446828....854736.. "-446828" "854736"
> 
> So far so good, but  columns 1:2 will not coerce to either numeric or
> integer, for unknown reasons.  Thanks for any help (and/or suggestions 
on a
> better way to code this).
> 
> 
> 
> Jim Bouldin, PhD
> Research Ecologist
> Department of Plant Sciences, UC Davis
> Davis CA, 95616
> 530-554-1740
> 
> ______________________________________________
> R-help at 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.

Try this:
> x <- c("-448623_854854", "-448563_854850",
"-448442_854842", "-448301_854833",
+ "-448060_854818",
"-446828_854736")
>
>
> read.table(textConnection(x), sep = "_")
       V1     V2
1 -448623 854854
2 -448563 854850
3 -448442 854842
4 -448301 854833
5 -448060 854818
6 -446828 854736

Here is another way.
> library(gsubfn) # see http://gsubfn.googlecode.com
>
> data.frame(strapply(x, "[-0-9]+", as.numeric, simplify = rbind))
       X1     X2
1 -448623 854854
2 -448563 854850
3 -448442 854842
4 -448301 854833
5 -448060 854818
6 -446828 854736

If you omit data.frame then it will return a matrix.


On Thu, May 6, 2010 at 8:12 AM, Jim Bouldin <jrbouldin at ucdavis.edu>
wrote:
>
> This seemingly should be quite simple but I can't solve it:
>
> I have a long character vector of geographic data (data frame column named
> "XY") whose elements vary in length (from 11 to 14 chars). ?Each
element is
> structured as a set of digits, then an underscore, then more digits, e.g:
>
>> data.frame(head(as.character(XY)))
> ?head.as.character.XY..
> 1 ? ? ? ? -448623_854854
> 2 ? ? ? ? -448563_854850
> 3 ? ? ? ? -448442_854842
> 4 ? ? ? ? -448301_854833
> 5 ? ? ? ? -448060_854818
> 6 ? ? ? ? -446828_854736
>
> I simply need to separate the two sets of digits from each other and assign
> them into new columns. ?The closest I've been able to get is by:
>
>> test=t(as.matrix(data.frame(head(strsplit(as.character(XY),
"\\_")))))
>> test
> ? ? ? ? ? ? ? ? ? ? ? [,1] ? ? ?[,2]
> c...448623....854854.. "-448623" "854854"
> c...448563....854850.. "-448563" "854850"
> c...448442....854842.. "-448442" "854842"
> c...448301....854833.. "-448301" "854833"
> c...448060....854818.. "-448060" "854818"
> c...446828....854736.. "-446828" "854736"
>
> So far so good, but ?columns 1:2 will not coerce to either numeric or
> integer, for unknown reasons. ?Thanks for any help (and/or suggestions on a
> better way to code this).
>
>
>
> Jim Bouldin, PhD
> Research Ecologist
> Department of Plant Sciences, UC Davis
> Davis CA, 95616
> 530-554-1740
>
> ______________________________________________
> R-help at 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.
>