R help - Jun 2010 - generate irregular series of dates

Dear colleagues, particularly academic ones,
So I'm creating a Microsoft Word template for myself so that every  
time I teach a new course, I don't have to enter in the dates manually  
for each class session.
I'd like to use an R script that can generate an irregular series of  
dates starting from one date (semester begin) to another (semester  
end) using an irregular interval in between (Tuesdays and Thursdays,  
for example).
I know that a regular series of dates is no problem, but what about an  
irregular series?
Yours,
Simon Kisss
*********************************
Simon J. Kiss, PhD
SSHRC and DAAD Post-Doctoral Fellow
John F. Kennedy Institute of North America Studies
Free University of Berlin
Lansstra?e 7-9
14195 Berlin, Germany
Cell: +49 (0)1525-300-2812,
Web: http://www.jfki.fu-berlin.de/index.html

Previously in R 2.9.2 I used the following to convert from an improperly
formatted NA string into one that is a bit more consistent.


gsub("N\A", "NA", "N\A", fixed=TRUE)

This worked in R 2.9.2, but now in R 2.11.1 it doesn't seem to work an
throws the following error.
Error: '\A' is an unrecognized escape in character string starting
"N\A"

I guess my questions are the following:
(1) Is this expected behavior? 
(2) If it is expected behavior, what is the proper way to replace
"N\A" with "NA" and "N\\A" with "NA"?

Thank you again for all the help and insight.

A fairly simple way is to generate one series with all the Tuesdays, then
another with all the Thursdays, combine and sort.
> sort( c( seq.Date( as.Date('2010-6-29'), by='week',
length.out=10),
+ seq.Date( as.Date('2010-7-1'), by='week', length.out=10) )
+ )
 [1] "2010-06-29" "2010-07-01" "2010-07-06"
"2010-07-08" "2010-07-13"
 [6] "2010-07-15" "2010-07-20" "2010-07-22"
"2010-07-27" "2010-07-29"
[11] "2010-08-03" "2010-08-05" "2010-08-10"
"2010-08-12" "2010-08-17"
[16] "2010-08-19" "2010-08-24" "2010-08-26"
"2010-08-31" "2010-09-02"
>
-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Simon Kiss
> Sent: Tuesday, June 29, 2010 4:22 AM
> To: r-help at r-project.org
> Subject: [R] generate irregular series of dates
> 
> Dear colleagues, particularly academic ones,
> So I'm creating a Microsoft Word template for myself so that every
> time I teach a new course, I don't have to enter in the dates manually
> for each class session.
> I'd like to use an R script that can generate an irregular series of
> dates starting from one date (semester begin) to another (semester
> end) using an irregular interval in between (Tuesdays and Thursdays,
> for example).
> I know that a regular series of dates is no problem, but what about an
> irregular series?
> Yours,
> Simon Kisss
> *********************************
> Simon J. Kiss, PhD
> SSHRC and DAAD Post-Doctoral Fellow
> John F. Kennedy Institute of North America Studies
> Free University of Berlin
> Lansstra?e 7-9
> 14195 Berlin, Germany
> Cell: +49 (0)1525-300-2812,
> Web: http://www.jfki.fu-berlin.de/index.html
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.

On Tue, Jun 29, 2010 at 6:22 AM, Simon Kiss <sjkiss at gmail.com>
wrote:
> Dear colleagues, particularly academic ones,
> So I'm creating a Microsoft Word template for myself so that every time
I
> teach a new course, I don't have to enter in the dates manually for
each
> class session.
> I'd like to use an R script that can generate an irregular series of
dates
> starting from one date (semester begin) to another (semester end) using an
> irregular interval in between (Tuesdays and Thursdays, for example).
> I know that a regular series of dates is no problem, but what about an
> irregular series?
Generate all the dates in the range of interest and then pick off the
Tuesdays and Thursdays:

dd <- seq(as.Date("2010-01-01"), as.Date("2010-12-31"),
"day")
dd[weekdays(dd) %in% c("Tuesday", "Thursday")]