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Ploticus date processing
Ploticus can plot dates directly and do date arithmetic.
Many details of date processing, including localization of month and weekday names,
can be controlled via settings in
proc settings
or in your
config file.
There are also a number of
functions
that deal with dates.
Plottable date notations
The following date notations are supported for plotting and date arithmetic:
Month, day, and year notations:
mm-dd-yy (example: 03-31-99)
mm-dd-yyyy (example: 03-31-1999)
mm/dd/yy (example: 03/31/99)
dd-mm-yy (example: 31-03-99)
dd/mm/yyyy (example: 31/03/99)
ddmmmyyyy (example: 31mar1999 or 31MAR99)
dd-mmm-yy (example: 31-mar-99 or 31-MAR-99)
mm/dd/yyyy mmddyyyy mm.dd.yy mm.dd.yyyy
mmm-dd-yy mmm-dd-yyyy mmm_dd_yy mmm_dd_yyyy
mmm/dd/yy mmm/dd/yyyy
dd-mm-yy dd-mm-yyyy dd/mm/yy dd/mm/yyyy
ddmmyy dd.mm.yy dd.mm.yyyy
dd-mmm-yyyy dd_mmm_yy dd_mmm_yyyy
dd/mmm/yy dd/mmm/yyyy ddmmmyy ddmmmyyyy
yy-mm-dd yy/mm/dd yymmdd yy.mm.dd
yyyy-mm-dd yyyy/mm/dd yyyymmdd yyyy.mm.dd
yyyy-mmm-dd yyyy_mmm_dd yyyymmmdd
Month & year notations
(a day value of 01 is used internally for arithmetic/plotting purposes):
mm/yyyy (example: 03/1999)
Others:
yy/mm yy-mm yyyymm yyyy/mm yyyy-mm
mm/yy mm-yy mm-yyyy
Quarter year notations
(day and month will be set to mid-quarter for arithmetic/plotting purposes):
yyqn (example: 99q1 or 99Q1)
nqyyyy (example: 1q1999 or 1Q1999)
Year only notation
yy (uses pivot year, so 00 is greater than 99)
Basic unit
The basic date unit is always a day, regardless
of which notation is in use. Stub and tic increments
may be expressed in months or years, if desired.
Setting date notation
Any date value to be plotted or involved in date arithmetic must
conform to the current date notation.
The default notation is mmddyy.
In scripts, the date notation can be set using the
xscaletype or yscaletype attributes of
proc areadef
, using
proc settings
or by using a
config file.
You can also set the date format at anytime using something like this in scripts:
#call $setdateformat( mm/dd/yyyy )
Display-only notations
In addition to the above plottable notations,
the following additional notations may be used only for
displaying dates (such as with the stubformat
attribute, for instance). They may not be used for
date plotting or arithmetic.
Full dates for presentation:
month_dd,_yyyy (or full) (example: March 31, 1999)
mon_dd,_yyyy (example: Mar 31, 1999)
dd_month,_yyyy (example: 31 March, 1999)
dd_mon,_yyyy (example: 31 Mar, 1999)
Www_dd_mon,_yyyy (or wfull) (example: Wed 31 Mar, 1999)
Month & year only: mmyy, mmyyyy
Month & day only: mmmdd, mmm/dd, mmm-dd, mmm_dd, mm/dd, mm-dd, mm_dd, dd-mmm, dd/mmm, ddmmm
Year only: 'yy, yyyy
Month only: mmm, mm, m
Day only: dd d
Weekday:
W (example: S M T W T F S)
Www (example: Sun Mon Tue Wed Thu Fri Sat)
Key to notation codes
m = single character month (use M for capitalized)
mm = numeric month 01-12
mmm = three-character month e.g. jan (use MMM for JAN or Mmm for Jan)
mon = month abbreviation e.g. Jan
month = full month e.g. January
dd = numeric day 01-31
d = numeric day 1-31
yy = numeric year 00-99
yyyy = numeric year 1800-up
w = single character weekday (use W for capitalized)
www = three character weekday (use Www or WWW for capitalized)
n = 1, 2, 3 or 4 (quarter year notations)
q = the letter q or Q (quarter year notations)
_ (underscore) = space
Notes
1. It is possible to omit weekends. This is usually done
in business- or market-related plots. To omit weekends,
set the omitweekends attribute in
proc settings
or
your config file,
or using the
$setdateparms() function.
Note: as of version 2.30 weekend omission is not supported (and gives incorrect results) for dates
before julian 0 date (Jan 1 1970).
2. Date values may or may not be required to adhere exactly to
the date format. For instance, if the format is mm/dd/yyyy
a value such as 03/04/2001 is always legal, but a value such as
3/4/2001 may not be.
Apparently spreadsheets often export dates such as the latter.
See the strictdatelengths parameter in
proc settings
and/or your
ploticus config file,
or using the
$setdateparms() function.
By default, ploticus operates in lenient mode.
Use strict mode to ensure that malformed dates will be detected.
3. Dates use an internal julian date system where 0 = January 1, 1970.
Dates as far back as 1754 AD can be handled.
4. Conversion from two-digit dates to four digit dates is
achieved using a pivot year- any two digit year less than
this value is assumed to be 21st century.
The default pivot year is 70.
It can be set via
proc settings
or in your
ploticus config file,
or using the
$setdateparms() function.
5. When three-character months are used, they are always
entered and stored as lower case; however the capitalization
of the "mmm" can be altered to control the way dates are
presented, e.g. Mmm = Jan, MMM = JAN.
6. "Lazy" dates may be used.
A lazy date has 00 as the day and/or month portion and is usually
used in situations where the day and/or month is unknown or unavailable.
When a lazy date is used in date arithmetic the
missing month and/or day is converted to 01.
By default, lazy dates are not permitted for date arithmetic.
7. When using notations that do not contain a specific day
(such as month year, quarter year, or year only)
there may be occasions when it is necessary to specify an
exact day point (for example to create an annotation).
To do this, an alternate full date format may be used.
For example, if yyqn notation is being used,
full dates may be given in yy/mm/dd format.
Alternate full-
Notation date notation
------------------- -----------
yymm yymmdd
yymmm ddmmmyy
yy/mm, yy-mm, etc. yy/mm/dd
yyyy/mm, yyyy-mm, etc. yyyy/mm/dd
yy yymmdd
mm/yy, mm-yy, etc. dd/mm/yy
mm/yyyy, mm-yyyy, etc. dd/mm/yyyy
yyqn yy/mm/dd
yyyyqn yyyy/mm/dd
nqyy yy/mm/dd
nqyyyy yyyy/mm/dd
