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Re: IDL 5.4 label_date function [message #27810 is a reply to message #27802]

Wed, 07 November 2001 07:51

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Chad Bahrmann (cbahrmann@ou.edu) writes:

> Has anyone encountered problems in using the label_date function in IDL 5.4?
> From the documentation for IDL 5.4. This plot gives you data from
> 11/01/2001 at 1200 through 11/02/2001 at 1200 when I would expect data from
> 11/01/2001 at 0000 through 11/02/2001 at 0000. I have had success using
> this function in older versions of IDL but this one appears not to work
> properly? The actual code had revisions on
> ; MODIFICATION HISTORY:
> ; DMS, RSI. April, 1993. Written.
> ; DMS, RSI. March, 1997. Added Time format.
> ; DMS, RSI. Jan, 1999. Rounded least significant time unit
> ; CT, RSI. May 2000. Completely rewrote to use calendar format codes.
> ; Added Level argument for new date/time TICKUNITS.
> ; Added AM_PM and DAYS_OF_WEEK keywords, '%A' and '%W' codes.
> ;-
>
> PRO test
>
> ; Create format strings for a two-level axis:
>
> dummy = LABEL_DATE(DATE_FORMAT=['%H%I!C%N/%D/%Y'])
>
> ;Generate the Date/Time data
> time = TIMEGEN(START=JULDAY(11,1,2001), FINAL=JULDAY(11,2,2001))
>
> ;Generate the Y-axis data
> data = RANDOMN(seed, N_ELEMENTS(time))
>
> ;Plot the data
> PLOT, time, data, XTICKUNITS = ['Time'], $
> XTICKFORMAT='LABEL_DATE', XSTYLE=1, XTICKS=6, YMARGIN=[6,2]
>
>
> end

I don't know. The second paragraph in the TIMEGEN
documentation seems pretty clear:

The Julian date is the number of days elapsed
since Jan. 1, 4713 B.C.E., plus the time expressed
as a day fraction. Following the astronomical
convention, the day is defined to start at 12 PM
(noon). Julian date 0.0d is therefore Jan. 1,
4713 B.C.E. at 12:00:00.

Cheers,

David

--
David W. Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		Re: IDL 5.4 label_date function By: Wayne Landsman on Wed, 07 November 2001 14:54
		Re: IDL 5.4 label_date function By: Chad Bahrmann on Wed, 07 November 2001 14:37
		Re: IDL 5.4 label_date function By: Mark Hadfield on Wed, 07 November 2001 13:01
		Re: IDL 5.4 label_date function By: Mark Hadfield on Wed, 07 November 2001 12:45
		Re: IDL 5.4 label_date function By: Craig Markwardt on Wed, 07 November 2001 10:57
		Re: IDL 5.4 label_date function By: David Fanning on Wed, 07 November 2001 07:51

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