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label_date.pro

This function labels axes with dates and times.

label_date Plotting

result = label_date(axis, index, x, DATE_FORMAT=DATE_FORMAT, MONTHS=MONTHS, OFFSET=OFFSET, _EXTRA=_EXTRA)

Parameters

axis        in

index        in

x        in

Keywords

DATE_FORMAT       

a format string which may contain the following: %M for month (3 characters abbr) %N for month (2 digits abbr) %D for day of month, %Y for 4 digits year. %Z for last two digits of year. For time: %H for Hours, 2 digits. %I for Minutes, 2 digits. %S for Seconds, 2 digits. %% is %. Other characters are passed directly thru. For example, '%M %D, %Y' prints DEC 11, 1993 '%M %2Y' yields DEC 93 '%D-%M' yields 11-DEC '%D/%N/%Y' yields 11/12/1993 '%M!C%Y' yields DEC on the top line, 1993 on the bottom (!C is the new line graphic command).

MONTHS       

The names of the months, a twelve element string array. If omitted, use Jan, Feb, ..., Dec.

OFFSET       

An optional starting offset of the plot. Unfortunately, single precision floating point is not accurate enough to properly represent Julian times. This offset, which may be double precision, contains an offset that is added to all x values, before conversion to Julian date and time.

_EXTRA       

Examples


 For example, to plot from Jan 1, 1993, to July 12, 1994:

   IDL> Start_date = julday(1, 1, 1993)
   IDL> End_date = julday(7, 12, 1994)
   IDL> ; Simple mm/dd
   IDL> Dummy = LABEL_DATE(DATE_FORMAT='%N/%D')
   IDL> ;Time axis
   IDL> x = findgen(end_date+1 - start_date) + start_date
   IDL> ; Plot with X axis style set to exact
   IDL> PLOT, x, sqrt(x), XTICKFORMAT = 'LABEL_DATE', XSTYLE=1

 Example with times:

 For example, to plot from 3PM, Jan 1, 1993, to 5AM, Jan 3, 1993:

   IDL> ; Also starting offset
   IDL> Start_date = Julday(1,1,1993)
   IDL> ; Starting_time less offset
   IDL> Start_time = (3+12)/24.
   IDL> End_time = (Julday(1,3,1993) - Start_date) + 5./24.
   IDL> ; Ending date/time - offset, note that the order of operations is
   IDL> ; important to avoid loss of precision
   IDL> ; MMM NN  HH:MM format
   IDL> Dummy = LABEL_DATE(DATE_FORMAT='%D %M!C%H:%I', offset=Start_date)
   IDL> ;Time axis
   IDL> x = findgen(20) * (End_time - Start_time) / 19 + start_time
   IDL> PLOT, x, sqrt(x), XTICKFORMAT = 'LABEL_DATE', XSTYLE=1

Version history

Version

$Id: label_date.pro 371 2008-08-07 09:32:02Z pinsard $

History

DMS, RSI. April, 1993. Written. DMS, RSI. March, 1997. Added Time format. Copyright (c) 1993-1998, Research Systems, Inc. All rights reserved. Unauthorized reproduction prohibited.

Known issues

Restrictions

Only one date axis may be simultaneously active.

Other attributes

Uses routines

Common blocks used

label_date_com

 

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