Re: Dates and Times in S-Plus

["Eric Zivot" <ezivot@u.washington.edu>]

You can also subset timeDate and timeSeries objects directly using the timeEvent function. For example, to index the elements of the FinMetrics timeSeries singleIndex.dat between the periods 3/1/1992 and 1/31/1993 use

 

> singleIndex.dat[timeEvent("3/1/1992", "1/31/1993")]

 

This trick is extremely helpful in plotting subsets of timeSeries data, but it only works in splus 7 and above.

 

 

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From: s-news-owner@lists.biostat.wustl.edu [mailto:s-news-owner@lists.biostat.wustl.edu] On Behalf Of David L Lorenz
Sent: Friday, April 06, 2007 11:18 AM
To: Kim Elmore
Cc: S-News; s-news-owner@lists.biostat.wustl.edu
Subject: Re: [S] Dates and Times in S-Plus

Kim, 
  There are a lot of thing to consider when making 
plots of date/time data, including getting ticks in the correct place and 
correct labels. We are trying to develop functions that will plot the data 
correctly and get nice ticks and correct labels. I don't have anything for 
hourly data right now, but when we do get a good product, those functions will 
be publically available.  Here's basically the approach I would 
take: 

1. For the GUI and command, 
I'd generate a data.frame that contains the ticks and labels I wanted. Use the 
timeSeq() function to generate ticks: 
> timeSeq("11/29/2007 14:15:00", by='hours', length.out=6, align.by=T, 
extend=T) 
[1] 11/29/2007 14:00:00.000 
11/29/2007 15:00:00.000 11/29/2007 16:00:00.000 
[4] 11/29/2007 17:00:00.000 11/29/2007 18:00:00.000 11/29/2007 
19:00:00.000 
Use the hms() function on 
those data to extract the hour and put that into another column for the labels. 
You can further format them any way you wish. 

2. For the GUI plot, set the major ticks to use a column 
in a separate data set and choose the one you created in step one. Do the same 
for labels. 

3. To subset the data, 
use something like: 
DateTime >= 
timeDate("11/29/2007 14:15:00") & DateTime <= timeDate("11/29/2007 18:15:00") 
in your subsetting _expression_, assuming that 
the date/time column name is DateTime. 

4. For the command line version, I'd convert everything to double for the 
date/time axis, set the axis type to 'i' or 's' and not draw anything on that 
axis. Then go back and draw the axis, put in the ticks and labels. 

  Good luck. 
Dave

Kim Elmore <Kim.Elmore@noaa.gov>
Sent by: s-news-owner@lists.biostat.wustl.edu

04/06/2007 11:16 AM

To	S-News <s-news@wubios.wustl.edu>
cc
Subject	[S] Dates and Times in S-Plus

I've never much worked with dates and times, but find that I must now 
do 
so. I'm doing some very basic EDA and using the GUI to generate some 
plots. When making plots using the GUI, how do I control the span of the 
date axis? I'm aware that S-Plus encodes the date in a manner similar to 
unix/linux, but I don't know how to define things like tic marks in 
terms of, say hours. For example, if I want a tic mark every hour, how 
do I declare that? Using command line plots, how would I subset the data 
such that I plotted only data between, say, 11/29/2007 14:15:00 and 
11/29/2007 18:15:00?

All data are currently in a data.frame and the 
data type for the dates 
column is timeDate.

I'm using S-Plus 7.0.6 
under Windows XP.

Kim 
Elmore
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