On Jun 12, 2008, at 5:06 PM, Marc Schwartz wrote:
on 06/12/2008 03:46 PM Hua Li wrote:
Hi,
I'm looking for some way to pick up the numbers which are
contained and buried in a long character. For example,
outtree.new="(((B:1204.25,E:1204.25):7581.11,F:8785.36):8353.85,C:
17139.21);"
num.char = unlist(strsplit(unlist(strsplit(unlist(strsplit(unlist
(strsplit(unlist(strsplit
(outtree.new,")",fixed=TRUE)),"(",fixed=TRUE)),":",fixed=TRUE)),",",f
ixed=TRUE)),";",fixed=TRUE))
num.vec=as.numeric(num.char[1:(length(num.char)-1)])
num.char
# "B" "1204.25" "E" "1204.25" "7581.11"
"F" "8785.36" "8353.85" "C" "17139.21" "" num.vec
# NA 1204.25 NA 1204.25 7581.11 NA 8785.36
8353.85 NA 17139.21
would help me get the numbers such as 1204.25, 7581.11, etc, but
with a warning message which reads:
"Warning message:
NAs introduced by coercion "
Is there a way to get around this? Thanks!
Hua
Your code above is overly and needlessly complicated, which makes
it difficult to debug.
I would take an approach whereby you use gsub() to strip non-
numeric characters from the input character vector and then use scan
() to read the remaining numbers:
> Vec <- scan(textConnection(gsub("[^0-9\\.]+", " ", outtree.new)))
Read 6 items
> Vec
[1] 1204.25 1204.25 7581.11 8785.36 8353.85 17139.21
> str(Vec)
num [1:6] 1204 1204 7581 8785 8354 ...
The result of using gsub() above is:
> gsub("[^0-9\\.]+", " ", outtree.new)
[1] " 1204.25 1204.25 7581.11 8785.36 8353.85 17139.21 "
That gives you a character vector which can then be passed to scan
() as a textConnection().
Another approach would be to split on sequences of non-integers:
as.numeric( strsplit(outtree.new, "[^\\d.]+", perl=TRUE)[[1]] )
Use "[^+-\\d.]+" if your numbers might be signed. This does assume
that dots, +/- occur only as decimal points.
Hua, did you want to keep the information of which number is B, which
is C etc?
See ?gsub, ?regex, ?textConnection and ?scan for more information.
HTH,
Marc Schwartz
Haris Skiadas
Department of Mathematics and Computer Science
Hanover College
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