I (and you as well) should have seen that before: use write.table in
order to append. The reason for that is given in ?write.table / ?write.csv:
‘write.csv’ and ‘write.csv2’ provide convenience wrappers for
writing CSV files. They set ‘sep’ and ‘dec’ (see below), ‘qmethod
= "double"’, and ‘col.names’ to ‘NA’ if ‘row.names = TRUE’ (the
default) and to ‘TRUE’ otherwise.
‘write.csv’ uses ‘"."’ for the decimal point and a comma for the
separator.
‘write.csv2’ uses a comma for the decimal point and a semicolon
for the separator, the Excel convention for CSV files in some
Western European locales.
These wrappers are deliberately inflexible: they are designed to
ensure that the correct conventions are used to write a valid
file. Attempts to change ‘append’, ‘col.names’, ‘sep’, ‘dec’ or
‘qmethod’ are ignored, with a warning.
Uwe Ligges
On 08.02.2012 20:29, Ron Michael wrote:
Okay, so I understood that appending can only happen row-wise. Therefore I
tried with following code:
write.csv(matrix(1:5, 1), "dat.csv")
write.csv(matrix(1:5, 1), "dat.csv", append = TRUE)
Warning message:
In write.csv(matrix(1:5, 1), "dat.csv", append = TRUE) :
attempt to set 'append' ignored
It is destroying my previous file. Where I have done wrong?
Thanks,
----- Original Message -----
From: Uwe Ligges<lig...@statistik.tu-dortmund.de>
To: Ron Michael<ron_michae...@yahoo.com>
Cc: "r-help@r-project.org"<r-help@r-project.org>
Sent: Thursday, 9 February 2012 1:07 AM
Subject: Re: [R] Wriritng to a CSV file
On 08.02.2012 20:14, Ron Michael wrote:
Dear all, let say I want to write a vector to a CSV file. So I can have
following syntax:
write.csv(rnorm(10), "dat.csv")
Now I want to add one more column into that existing file. If I use the same
code then existing file will be destroyed. Is there any functionality to add
without destroying the existing file? I have tries with 'append = TRUE' however
it is not working!
Any suggestion will be highly appreciated.
Since these text files are written line by line, you cannot add a column
afterwards, you can just append rows.
Hence read the first column and write a two column data.frame afterwards.
Uwe Ligges
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