ToBeReviewed/PLOTS/LABEL/
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
Produced by IDLdoc 2.0.