IS there a way we can append row wise, so that it all stacks up
horizontally, the way you do it in xlswrite in matlab, where you can even
specify the cell number from where you want to write.

-Ashish

 

From: R. Michael Weylandt [mailto:michael.weylandt@gmail.com] 
Sent: Thursday, September 22, 2011 12:03 AM
To: Jan van der Laan
Cc: r-help@r-project.org; ashish.kumar@esteeadvisors.com
Subject: Re: [R] R help on write.csv

 

Oh darn, I had that line and then when I copied it to gmail I thought I'd be
all slick and clean up my code: oh well...just not my day/thread...

It's possible to work around the repeated headers business (change to
something like "Call$col.names <- !append") but yeah, at this point I'm
thinking its perhaps better practice to direct the OP to the various
connection methods: sink() is nice, but he'll probably have to do something
to convert his object to a CSV like string before printing: 

apply(OBJ, 1, paste, sep=",")

Michael Weylandt

On Wed, Sep 21, 2011 at 11:20 AM, Jan van der Laan <eoos@dds.nl> wrote:

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.weylandt@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.calandra@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.weylandt@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.kumar@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.kumar@esteeadvisors.com

Cell: +91-9654072144 <tel:%2B91-9654072144> 

Direct: +91-124-4637-713 <tel:%2B91-124-4637-713> 




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