Williams, Robin wrote:
Hi all,
Is there an equivalent to the general * operator in R, where * can
represent any character?
I have a dataset, one column being date, date ranging between
April-September, 97-06. I would like to be able to acquire the data for
a specific month, say September, so that I can take average temperatures
for the month, etc. I thought I would be able to do something like
data.s1 <- subset(data,date=="**-Sep-**")
data.s1
but when I do
data.s1
I get "0 rows or 0-length row.names".
Any idea of a simple way I can perform this task?
All dates are in the form xx-xxx-xx, EG 30-Sep-06.
Thanks for any assistance.
grep() and related functions described on the same man page can match
general regular expressions. The pattern you want would be
"^..-Sep-..$". Read the man page; they have several options for output
format. They work on character vectors; if your data has already been
converted to a date format, there are likely other options, e.g.
converting the date with format %b (see ?strftime) so only the month is
included.
Duncan Murdoch
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