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# units

## `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 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 a converter
    units.registry[datetime.date] = DateConverter()

class `matplotlib.units.``AxisInfo`(majloc=None, minloc=None, majfmt=None, minfmt=None, label=None, default_limits=None)

  Bases: `object`

  information to support default axis labeling and tick labeling, and default limits

  majloc and minloc: TickLocators for the major and minor ticks majfmt and minfmt: TickFormatters for the major and minor ticks label: the default axis label default_limits: the default min, max of the axis if no data is present If any of the above are None, the axis will simply use the default

class `matplotlib.units.``ConversionInterface`

  Bases: `object`

  The minimal interface for a converter to take custom instances (or sequences) and convert them to values mpl can use

  static `axisinfo`(unit, axis)

    return an units.AxisInfo instance for axis with the specified units

  static `convert`(obj, 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

  static `default_units`(x, axis)

    return the default unit for x or None for the given axis

  static `is_numlike`(x)

    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. Derived conversion interfaces may opt to pass plain-ol unitless numbers through the conversion interface and this is a helper function for them.

class `matplotlib.units.``Registry`

  Bases: `dict`

  register types with conversion interface

  `get_converter`(x)

    get the converter interface instance for x, or None