On 11-01-13 6:26 AM, Rainer M Krug wrote:
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Hi
Assuming the following:
x<- data.frame(a=1:10, b=runif(10))
str(x)
'data.frame': 10 obs. of 2 variables:
$ a: int 1 2 3 4 5 6 7 8 9 10
$ b: num 0.692 0.325 0.634 0.16 0.873 ...
write.csv(x, "x.csv")
x2<- read.csv("x.csv")
str(x2)
'data.frame': 10 obs. of 3 variables:
$ X: int 1 2 3 4 5 6 7 8 9 10
$ a: int 1 2 3 4 5 6 7 8 9 10
$ b: num 0.692 0.325 0.634 0.16 0.873 ...
Using the two functions write.csv and read.csv, I would assume, that the
resulting data.frame x2 be identical with x, but it has an additional
column X, which contains the row names of x.
I know read.table and write.table which work as expected, but I would
like to use a csv for data exchange reasons.
I know that I can use
write.csv(x, "x.csv", row.names=FALSE)
and it would work, but shouldn't that be the default behaviour?
I don't think so. The CSV format is an export format which holds less
information than a dataframe. By exporting the dataframe to CSV and
importing the result, you are discarding information and you should
expect to get something different.
If you want to save a dataframe to disk and read it back unchanged, you
should use save() and load().
Duncan Murdoch
And if this is not compliant with csv files, shouldn't the function
read.csv convert the first column into the row names?
Cheers,
Rainer
- --
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)
Centre of Excellence for Invasion Biology
Natural Sciences Building
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Stellenbosch University
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email: rai...@krugs.de
Skype: RMkrug
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