On Apr 16, 2010, at 4:42 PM, Jeroen Ooms wrote:
Ah Phil Spector is right, nothing is converted. I'm almost too
embarrassed to
admit it, but actually, it was Excel that tricked me. It displays date
fields differently than they are stored in the csv file, and once
you press
'save', it saves everything to a different format, completely unasked.
Nevertheless I got some valuable insight in the topic. What I'm
trying to do
here is make it easier for people to upload files that might contain
dates
to my webapp at yeroon.net/ggplot2. Currently, dates are imported as
factors.
Only if one does not use as.is=TRUE
I would like to implement something that Henrique described, to
automatically convert variables to Date that are obviously dates.
If they are in YYYY-MM-DD format then colClasses is the way forward.
If you want to program a recognition strategy when you do not in
advance know the position of the date fields, then use readLines to
get a few lines and parse the fields and use Dallazuanna's regex
search for an "nnnn-nn-nn" pattern (perhaps with a "^|
whitespace<pattern>whitespace|$" wrapper around that pattern to avoid
Social Security fields or similar).
I suspect most experienced useRs would rather not have automatic data
conversion. Your request appears to be emulating a "feature" that is
considered undesirable Excel behavior.
--
David Winsemius, MD
West Hartford, CT
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