R help - Oct 2009 - extract day or month as in Splus

Dear all,

 

I am writing to ask for help to find R code to do the same thing as the
following Splus code:

 

dates <- c("02/27/1992", "02/27/1992",
"01/14/1992", "02/28/1992",
"02/01/1992")

timeDate(as.character(dates),in.format="%m/%d/%Y","%a")

[1] Thu Thu Tue Fri Sat

 

Could anyone give me some R codes to get the same results as above(extract
days from dates), please?

 

Thanks in advance!

 

Betty


	[[alternative HTML version deleted]]

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Fang (Betty) Yang
> Sent: Friday, October 23, 2009 11:06 AM
> To: R-help at r-project.org
> Subject: [R] extract day or month as in Splus
> 
> Dear all,
> 
>  
> 
> I am writing to ask for help to find R code to do the same 
> thing as the
> following Splus code:
> 
>  
> 
> dates <- c("02/27/1992", "02/27/1992",
"01/14/1992", "02/28/1992",
> "02/01/1992")
> 
> timeDate(as.character(dates),in.format="%m/%d/%Y","%a")
> 
> [1] Thu Thu Tue Fri Sat
You can use the POSIXct class to store the dates (instead
of the S+ timeDate class) and strftime() to format the output
(instead of attaching a default output format to the timeDate
object):

   > strftime(as.POSIXct(dates, format="%m/%d/%Y"),
format="%a")
   [1] "Thu" "Thu" "Tue" "Fri"
"Sat"

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com  
> 
>  
> 
> Could anyone give me some R codes to get the same results as 
> above(extract
> days from dates), please?
> 
>  
> 
> Thanks in advance!
> 
>  
> 
> Betty
> 
> 
> 	[[alternative HTML version deleted]]
> 
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> and provide commented, minimal, self-contained, reproducible code.
>

On Fri, 23 Oct 2009 12:06:28 -0600 Fang (Betty) Yang 
<fang.yang at ualberta.ca> wrote:
> dates <- c("02/27/1992", "02/27/1992",
"01/14/1992", "02/28/1992",
> "02/01/1992")
>
> Could anyone give me some R codes to get the same results as above'
> (extract days from dates), please?
If your dates are real dates, and not just character strings, the 
simplest way is to use the 'weekdays' functions. For you data:

# Convert the character strings to dates
dates=as.Date(dates, format="%m/%d/%Y")

# Extract the day names (note that these are localised day names)
weekdays(dates)

See the help file for 'weekdays' for details.

-- 
Karl Ove Hufthammer