matplotlib.units
¶The classes here provide support for using custom classes with
Matplotlib, e.g., those that do not expose the array interface but know
how to convert themselves to arrays. It also supports classes with
units and units conversion. Use cases include converters for custom
objects, e.g., a list of datetime objects, as well as for objects that
are unit aware. We don’t assume any particular units implementation;
rather a units implementation must provide the register with the Registry
converter dictionary and a ConversionInterface
. For example,
here is a complete implementation which supports plotting with native
datetime objects:
import matplotlib.units as units
import matplotlib.dates as dates
import matplotlib.ticker as ticker
import datetime
class DateConverter(units.ConversionInterface):
@staticmethod
def convert(value, unit, axis):
'Convert a datetime value to a scalar or array'
return dates.date2num(value)
@staticmethod
def axisinfo(unit, axis):
'Return major and minor tick locators and formatters'
if unit!='date': return None
majloc = dates.AutoDateLocator()
majfmt = dates.AutoDateFormatter(majloc)
return AxisInfo(majloc=majloc,
majfmt=majfmt,
label='date')
@staticmethod
def default_units(x, axis):
'Return the default unit for x or None'
return 'date'
# Finally we register our object type with the Matplotlib units registry.
units.registry[datetime.date] = DateConverter()
matplotlib.units.
AxisInfo
(majloc=None, minloc=None, majfmt=None, minfmt=None, label=None, default_limits=None)¶Bases: object
Information to support default axis labeling, tick labeling, and
default limits. An instance of this class must be returned by
ConversionInterface.axisinfo()
.
Parameters: | majloc, minloc : Locator, optional
majfmt, minfmt : Formatter, optional
label : str, optional
default_limits : optional
|
---|
Notes
If any of the above are None
, the axis will simply use the
default value.
matplotlib.units.
ConversionInterface
¶Bases: object
The minimal interface for a converter to take custom data types (or sequences) and convert them to values Matplotlib can use.
axisinfo
(axis)¶Return an AxisInfo
instance for the axis with the
specified units.
convert
(unit, axis)¶Convert obj using unit for the specified axis. If obj is a sequence, return the converted sequence. The output must be a sequence of scalars that can be used by the numpy array layer.
default_units
(axis)¶Return the default unit for x or None
for the given axis.
is_numlike
()¶The Matplotlib datalim, autoscaling, locators etc work with scalars which are the units converted to floats given the current unit. The converter may be passed these floats, or arrays of them, even when units are set.