On Aug 5, 2010, at 3:05 PM, David Winsemius wrote:
On Aug 5, 2010, at 2:48 PM, Archana Dayalu wrote:
Hello,
I am using read.table to read files directly from a public ftp
site. I have
a general list of files that may or may not exist in the ftp
directory, but
my hope was that R would read the file if it existed and ignored it
if it
didn't exist and move on to the next one. However, when R arrives
at a file
that does not exist I get the error message "Error in file(file,
"rt") :
cannot open the connection" This makes sense, but I was wondering
if there
was any way I could circumvent this error message and have R
instead give me
a warning message without terminating my entire loop.
Yes.
?try
Ideally, I would get a
warning message saying the connection does not exist, and then have
R skip
to the next file.
My code is copied below.
Something like these modifications .... untested:
Tried and discovered I need to remove the line feeds that broke the
file name assignment as well as adding 2 parens to close the if-test.
With those modifications you seem to be getting some sore of activity.
Aborting the run after a few access I see:
> str(r.obj.dat)
chr "alt.ch4.2000.dat.cont"
> str(alt.ch4.2000.dat.cont)
'data.frame': 8784 obs. of 10 variables:
$ DATE: chr "2000-01-01" "2000-01-01" "2000-01-01" "2000-01-01" ...
$ TIME: chr "01:00" "02:00" "03:00" "04:00" ...
$ DATE: chr "9999-99-99" "9999-99-99" "9999-99-99" "9999-99-99" ...
$ TIME: chr "99:99" "99:99" "99:99" "99:99" ...
$ CH4 : num -10000000 1864 1868 1863 1869 ...
$ ND : int 0 10 7 10 10 7 10 10 7 10 ...
$ SD : num -10 1.8 0.8 2.5 1.1 ...
$ F : int 0 1 1 1 1 1 1 1 1 1 ...
$ CS : int 0 0 0 0 0 0 0 0 0 0 ...
$ REM : int -99999999 -99999999 -99999999 -99999999 -99999999
-99999999 -99999999 -99999999 -99999999 -99999999 ...
>
hourly.years <- c(2000:2008)
hourly.species <- c('ch4','co2','co')
station.names <-
c
('alt482n00
','chm449n00
','egb444n01
','etl454n00','fsd449n00','llb454n01','wsa443n00','cdl453n00')
for (kk in hourly.years) {
for (i in hourly.species) {
for (nn in station.names) {
file1 <- paste('ftp://gaw.kishou.go.jp/pub/data/current/
',i,'/hourly/y',kk,'/',nn,'.ec.as.cn.',i,'.nl.hr',kk,'.anc',sep='')
#ancillary data
file2 <- paste('ftp://gaw.kishou.go.jp/pub/data/current/
',i,'/hourly/y',kk,'/',nn,'.ec.as.cn.',i,'.nl.hr',kk,'.dat',sep='')
#concentration data
dumm.anc <-
try( read.table(file1,skip=32,header=F,as.is=T) )
if (class(dumm.anc) == "try-error" {} else {
missing ")" about here .............^
colnames(dumm.anc) <- c('DATE','TIME','WD','WS','RH','AT')
r.obj.anc <- paste(substr(nn,1,3),i,kk,'anc.cont',sep='.')
assign(r.obj.anc,dumm.anc)
}
dumm.dat <-
try( read.table(file2,skip=32,header=F,as.is=T) )
if (class(dumm.dat) == "try-error" {} else { #will skip if error
missing ")" about here .............^
colnames(dumm.dat) <-
c('DATE','TIME','DATE','TIME','CH4','ND','SD','F','CS','REM')
r.obj.dat <- paste(substr(nn,1,3),i,kk,'dat.cont',sep='.')
assign(r.obj.dat,dumm.dat)
}
# --------------presumably these do not depend on the read-
tries---------
status<-paste(i,nn,kk,'----EC HOURLY/CONTINUOUS DAT/ANC
read
complete',sep=' ')
print(status,quote=F)
}
}
}
--
David Winsemius, MD
West Hartford, CT
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
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.
