Revision: 6830
http://matplotlib.svn.sourceforge.net/matplotlib/?rev=6830&view=rev
Author: jswhit
Date: 2009-01-26 19:48:04 +0000 (Mon, 26 Jan 2009)
Log Message:
-----------
update netcdftime to version 0.7, add date2index function.
Modified Paths:
--------------
trunk/toolkits/basemap/lib/mpl_toolkits/basemap/__init__.py
trunk/toolkits/basemap/lib/mpl_toolkits/basemap/netcdftime.py
Modified: trunk/toolkits/basemap/lib/mpl_toolkits/basemap/__init__.py
===================================================================
--- trunk/toolkits/basemap/lib/mpl_toolkits/basemap/__init__.py 2009-01-26
16:39:14 UTC (rev 6829)
+++ trunk/toolkits/basemap/lib/mpl_toolkits/basemap/__init__.py 2009-01-26
19:48:04 UTC (rev 6830)
@@ -17,6 +17,8 @@
:func:`num2date`: convert from a numeric time value to a datetime object.
:func:`date2num`: convert from a datetime object to a numeric time value.
+
+:func:`date2index`: compute a time variable index corresponding to a date.
"""
from matplotlib import __version__ as _matplotlib_version
from matplotlib.cbook import is_scalar, dedent
@@ -3941,6 +3943,42 @@
cdftime = netcdftime.utime(units,calendar=calendar)
return cdftime.date2num(dates)
+def date2index(dates, nctime, calendar=None):
+ """
+ Return indices of a netCDF time variable corresponding to the given dates.
+
+ .. tabularcolumns:: |l|L|
+
+ ============== ====================================================
+ Arguments Description
+ ============== ====================================================
+ dates A datetime object or a sequence of datetime objects.
+ The datetime objects should not include a
+ time-zone offset.
+ nctime A netCDF time variable object. The nctime object
+ must have a ``units`` attribute.
+ ============== ====================================================
+
+ .. tabularcolumns:: |l|L|
+
+ ============== ====================================================
+ Keywords Description
+ ============== ====================================================
+ calendar describes the calendar used in the time
+ calculations. All the values currently defined in
+ the CF metadata convention
+ (http://cf-pcmdi.llnl.gov/documents/cf-conventions/)
+ are supported.
+ Valid calendars ``standard``, ``gregorian``,
+ ``proleptic_gregorian``, ``noleap``, ``365_day``,
+ ``julian``, ``all_leap``, ``366_day``.
+ Default is ``proleptic_gregorian``.
+ ============== ====================================================
+
+ Returns an index or a sequence of indices.
+ """
+ return netcdftime.date2index(dates, nctime, calendar=None)
+
def maskoceans(lonsin,latsin,datain,inlands=False):
"""
mask data (``datain``), defined on a grid with latitudes ``latsin``
Modified: trunk/toolkits/basemap/lib/mpl_toolkits/basemap/netcdftime.py
===================================================================
--- trunk/toolkits/basemap/lib/mpl_toolkits/basemap/netcdftime.py
2009-01-26 16:39:14 UTC (rev 6829)
+++ trunk/toolkits/basemap/lib/mpl_toolkits/basemap/netcdftime.py
2009-01-26 19:48:04 UTC (rev 6830)
@@ -1,14 +1,13 @@
"""
Performs conversions of netCDF time coordinate data to/from datetime objects.
"""
-import math, re, time
-import numpy as np
+import math, numpy, re, time
from datetime import datetime as real_datetime
_units = ['days','hours','minutes','seconds','day','hour','minute','second']
_calendars =
['standard','gregorian','proleptic_gregorian','noleap','julian','all_leap','365_day','366_day','360_day']
-__version__ = '0.6'
+__version__ = '0.7'
class datetime:
"""
@@ -467,8 +466,8 @@
The B{C{calendar}} keyword describes the calendar used in the time
calculations.
All the values currently defined in the U{CF metadata convention
-<http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html#time>} are
-accepted. The default is C{'standard'}, which corresponds to the mixed
+<http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.1/cf-conventions.html#time-coordinate>}
+are accepted. The default is C{'standard'}, which corresponds to the mixed
Gregorian/Julian calendar used by the C{udunits library}. Valid calendars
are:
@@ -534,8 +533,7 @@
C{'standard'} or C{'gregorian'} calendars. An exception will be raised if you
pass
a 'datetime-like' object in that range to the C{L{date2num}} class method.
-Words of Wisdom from the British MetOffice concerning reference dates
-U{http://www.metoffice.com/research/hadleycentre/models/GDT/ch26.html}:
+Words of Wisdom from the British MetOffice concerning reference dates:
"udunits implements the mixed Gregorian/Julian calendar system, as
followed in England, in which dates prior to 1582-10-15 are assumed to use
@@ -560,8 +558,8 @@
@keyword calendar: describes the calendar used in the time calculations.
All the values currently defined in the U{CF metadata convention
-<http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html#time>} are
-accepted. The default is C{'standard'}, which corresponds to the mixed
+<http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.1/cf-conventions.html#time-coordinate>}
+are accepted. The default is C{'standard'}, which corresponds to the mixed
Gregorian/Julian calendar used by the C{udunits library}. Valid calendars
are:
- C{'gregorian'} or C{'standard'} (default):
@@ -630,7 +628,7 @@
except:
isscalar = True
if not isscalar:
- date = np.array(date)
+ date = numpy.array(date)
shape = date.shape
if self.calendar in
['julian','standard','gregorian','proleptic_gregorian']:
if isscalar:
@@ -657,7 +655,7 @@
else:
jdelta = [_360DayFromDate(d)-self._jd0 for d in date.flat]
if not isscalar:
- jdelta = np.array(jdelta)
+ jdelta = numpy.array(jdelta)
# convert to desired units, add time zone offset.
if self.units in ['second','seconds']:
jdelta = jdelta*86400. + self.tzoffset*60.
@@ -670,7 +668,7 @@
if isscalar:
return jdelta
else:
- return np.reshape(jdelta,shape)
+ return numpy.reshape(jdelta,shape)
def num2date(self,time_value):
"""
@@ -682,8 +680,8 @@
Resolution is 1 second.
-Works for scalars, sequences and np arrays.
-Returns a scalar if input is a scalar, else returns a np array.
+Works for scalars, sequences and numpy arrays.
+Returns a scalar if input is a scalar, else returns a numpy array.
The datetime instances returned by C{num2date} are 'real' python datetime
objects if the date falls in the Gregorian calendar (i.e.
@@ -700,7 +698,7 @@
except:
isscalar = True
if not isscalar:
- time_value = np.array(time_value)
+ time_value = numpy.array(time_value, dtype='d')
shape = time_value.shape
# convert to desired units, remove time zone offset.
if self.units in ['second','seconds']:
@@ -735,7 +733,7 @@
if isscalar:
return date
else:
- return np.reshape(np.array(date),shape)
+ return numpy.reshape(numpy.array(date),shape)
def _parse_date(origin):
"""Parses a date string and returns a tuple
@@ -852,3 +850,147 @@
for site in sites:
s = s[:site] + syear + s[site+4:]
return s
+
+def date2num(dates,units,calendar='standard'):
+ """
+date2num(dates,units,calendar='standard')
+
+Return numeric time values given datetime objects. The units
+of the numeric time values are described by the L{units} argument
+and the L{calendar} keyword. The datetime objects must
+be in UTC with no time-zone offset. If there is a
+time-zone offset in C{units}, it will be applied to the
+returned numeric values.
+
+Like the matplotlib C{date2num} function, except that it allows
+for different units and calendars. Behaves the same if
+C{units = 'days since 0001-01-01 00:00:00'} and
+C{calendar = 'proleptic_gregorian'}.
+
+...@param dates: A datetime object or a sequence of datetime objects.
+ The datetime objects should not include a time-zone offset.
+
+...@param units: a string of the form C{'B{time units} since B{reference
time}}'
+ describing the time units. B{C{time units}} can be days, hours, minutes
+ or seconds. B{C{reference time}} is the time origin. A valid choice
+ would be units=C{'hours since 1800-01-01 00:00:00 -6:00'}.
+
+...@param calendar: describes the calendar used in the time calculations.
+ All the values currently defined in the U{CF metadata convention
+ <http://cf-pcmdi.llnl.gov/documents/cf-conventions/>} are supported.
+ Valid calendars C{'standard', 'gregorian', 'proleptic_gregorian'
+ 'noleap', '365_day', '360_day', 'julian', 'all_leap', '366_day'}.
+ Default is C{'standard'}, which is a mixed Julian/Gregorian calendar.
+
+...@return: a numeric time value, or an array of numeric time values.
+
+The maximum resolution of the numeric time values is 1 second.
+ """
+ cdftime = utime(units,calendar=calendar)
+ return cdftime.date2num(dates)
+
+def num2date(times,units,calendar='standard'):
+ """
+num2date(times,units,calendar='standard')
+
+Return datetime objects given numeric time values. The units
+of the numeric time values are described by the C{units} argument
+and the C{calendar} keyword. The returned datetime objects represent
+UTC with no time-zone offset, even if the specified
+C{units} contain a time-zone offset.
+
+Like the matplotlib C{num2date} function, except that it allows
+for different units and calendars. Behaves the same if
+C{units = 'days since 001-01-01 00:00:00'} and
+C{calendar = 'proleptic_gregorian'}.
+
+...@param times: numeric time values. Maximum resolution is 1 second.
+
+...@param units: a string of the form C{'B{time units} since B{reference
time}}'
+describing the time units. B{C{time units}} can be days, hours, minutes
+or seconds. B{C{reference time}} is the time origin. A valid choice
+would be units=C{'hours since 1800-01-01 00:00:00 -6:00'}.
+
+...@param calendar: describes the calendar used in the time calculations.
+All the values currently defined in the U{CF metadata convention
+<http://cf-pcmdi.llnl.gov/documents/cf-conventions/>} are supported.
+Valid calendars C{'standard', 'gregorian', 'proleptic_gregorian'
+'noleap', '365_day', '360_day', 'julian', 'all_leap', '366_day'}.
+Default is C{'standard'}, which is a mixed Julian/Gregorian calendar.
+
+...@return: a datetime instance, or an array of datetime instances.
+
+The datetime instances returned are 'real' python datetime
+objects if the date falls in the Gregorian calendar (i.e.
+C{calendar='proleptic_gregorian'}, or C{calendar = 'standard'} or
C{'gregorian'}
+and the date is after 1582-10-15). Otherwise, they are 'phony' datetime
+objects which support some but not all the methods of 'real' python
+datetime objects. This is because the python datetime module cannot
+the uses the C{'proleptic_gregorian'} calendar, even before the switch
+occured from the Julian calendar in 1582. The datetime instances
+do not contain a time-zone offset, even if the specified C{units}
+contains one.
+ """
+ cdftime = utime(units,calendar=calendar)
+ return cdftime.num2date(times)
+
+
+def _check_index(indices, dates, nctime, calendar):
+ """Assert that the time indices given correspond to the given dates."""
+ t = nctime[indices]
+ assert numpy.all( num2date(t, nctime.units, calendar) == dates)
+
+
+def date2index(dates, nctime, calendar=None):
+ """
+ date2index(dates, nctime, calendar=None)
+
+ Return indices of a netCDF time variable corresponding to the given dates.
+
+ @param dates: A datetime object or a sequence of datetime objects.
+ The datetime objects should not include a time-zone offset.
+
+ @param nctime: A netCDF time variable object. The nctime object must have a
+ C{units} attribute.
+
+ @param calendar: Describes the calendar used in the time calculation.
+ Valid calendars C{'standard', 'gregorian', 'proleptic_gregorian'
+ 'noleap', '365_day', '360_day', 'julian', 'all_leap', '366_day'}.
+ Default is C{'standard'}, which is a mixed Julian/Gregorian calendar
+ If C{calendar} is None, its value is given by C{nctime.calendar} or
+ C{standard} if no such attribute exists.
+ """
+ # Setting the calendar.
+ if calendar is None:
+ calendar = getattr(nctime, 'calendar', 'standard')
+
+ num = numpy.atleast_1d(date2num(dates, nctime.units, calendar))
+
+ index = numpy.empty(numpy.alen(dates), int)
+
+ # Trying to infer the correct index from the starting time and the stride.
+ try:
+ t0, t1 = nctime[:2]
+ dt = t1 - t0
+ index[:] = (num-t0)/dt
+
+ # convert numpy scalars or single element arrays to python ints.
+ if not len(index.shape) or index.shape == (1,):
+ index = index.item()
+
+ # Checking that the index really corresponds to the given date.
+ _check_index(index, dates, nctime, calendar)
+
+ except AssertionError:
+ # If check fails, use brute force method.
+ index[:] = numpy.digitize(num, nctime[:]) - 1
+
+ # convert numpy scalars or single element arrays to python ints.
+ if not len(index.shape) or index.shape == (1,):
+ index = index.item()
+
+ # Perform check again.
+ _check_index(index, dates, nctime, calendar)
+
+ return index
+
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