Michael,
You example doesn't seem to work. Append isn't passed on to the
write.table call. You will need to add a
Call$append<- append
to the function. And even then there will be a problem with the
headers that are repeated when appending.
An easier solution is to use write.table directly (I am using
Dutch/European csv format):
data <- data.frame(a=1:10, b=1, c=letters[1:10])
write.table(data, file="test.csv", sep=";", dec=",", row.names=FALSE,
col.names=TRUE)
write.table(data, file="test.csv", sep=";", dec=",", row.names=FALSE,
col.names=FALSE,
append=TRUE)
When first openening a file connection and passing that to write.csv
or write.table data is also appended. The problem with write.csv is
that writing the column names can not be suppressed which will result
in repeated column names:
con <- file("d:test2.csv", "wt")
write.csv2(data, file=con, row.names=FALSE)
write.csv2(data, file=con, row.names=FALSE)
close(con)
So one will still have to use write.table to avoid this:
con <- file("d:test2.csv", "wt")
write.table(data, file=con, sep=";", dec=",", row.names=FALSE, col.names=TRUE)
write.table(data, file=con, sep=";", dec=",", row.names=FALSE,
col.names=FALSE,
append=TRUE)
close(con)
Using a file connection is probably also more efficient when doing a
large number of appends.
Jan
Quoting "R. Michael Weylandt" <michael.weyla...@gmail.com>:
Touche -- perhaps we could make one though?
write.csv.append <- function(..., append = TRUE)
{
Call <- match.call(expand.dots = TRUE)
for (argname in c("col.names", "sep", "dec", "qmethod")) if
(!is.null(Call[[argname]]))
warning(gettextf("attempt to set '%s' ignored", argname),
domain = NA)
rn <- eval.parent(Call$row.names)
Call$col.names <- if (is.logical(rn) && !rn)
TRUE
else NA
Call$sep <- ","
Call$dec <- "."
Call$qmethod <- "double"
Call[[1L]] <- as.name("write.table")
eval.parent(Call)
}
write.csv.append(1:5,"test.csv", append = FALSE)
write.csv.append(1:15, "test.csv")
Output seems a little sloppy, but might work for the OP.
Michael Weylandt
On Wed, Sep 21, 2011 at 9:03 AM, Ivan Calandra <ivan.calan...@uni-hamburg.de
wrote:
I don't think there is an append argument to write.csv() (well, actually
there is one, but set to FALSE).
There is however one to write.table()
Ivan
Le 9/21/2011 14:54, R. Michael Weylandt <michael.weyla...@gmail.com> a
écrit :
The append argument of write.csv()?
Michael
On Sep 21, 2011, at 8:01 AM, "Ashish Kumar"<ashish.kumar@**
esteeadvisors.com <ashish.ku...@esteeadvisors.com>> wrote:
Hi,
I wanted to write the data created using R on existing csv file. However
everytime I use write.csv, it overwrites the values already there in the
existing csv file. Any workaround on this.
Thanks for your help
Ashish Kumar
Estee Advisors Pvt. Ltd.
Email: ashish.ku...@esteeadvisors.com
Cell: +91-9654072144
Direct: +91-124-4637-713
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--
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Dept. Mammalogy
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calan...@uni-hamburg.de
**********
http://www.for771.uni-bonn.de
http://webapp5.rrz.uni-**hamburg.de/mammals/eng/1525_8_**1.php<http://webapp5.rrz.uni-hamburg.de/mammals/eng/1525_8_1.php>
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