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Backport PR #9314 on branch v3.1.x (Simplify units.Registry.get_converter.) #13547

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Merged
merged 1 commit into from
Feb 28, 2019
Merged

Backport PR #9314 on branch v3.1.x (Simplify units.Registry.get_converter.) #13547

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100 changes: 30 additions & 70 deletions lib/matplotlib/units.py
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Original file line number Diff line number Diff line change
Expand Up @@ -55,9 +55,10 @@ class ConversionError(TypeError):

class AxisInfo(object):
"""
Information to support default axis labeling, tick labeling, and
default limits. An instance of this class must be returned by
:meth:`ConversionInterface.axisinfo`.
Information to support default axis labeling, tick labeling, and limits.

An instance of this class must be returned by
`ConversionInterface.axisinfo`.
"""
def __init__(self, majloc=None, minloc=None,
majfmt=None, minfmt=None, label=None,
Expand Down Expand Up @@ -96,8 +97,7 @@ class ConversionInterface(object):
@staticmethod
def axisinfo(unit, axis):
"""
Return an `~units.AxisInfo` instance for the axis with the
specified units.
Return an `~units.AxisInfo` for the axis with the specified units.
"""
return None

Expand All @@ -112,19 +112,19 @@ def default_units(x, axis):
def 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.

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.
"""
return obj

@staticmethod
def 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.
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.
"""
if np.iterable(x):
for thisx in x:
Expand All @@ -134,73 +134,33 @@ def is_numlike(x):


class Registry(dict):
"""
A register that maps types to conversion interfaces.
"""
def __init__(self):
dict.__init__(self)
self._cached = {}
"""Register types with conversion interface."""

def get_converter(self, x):
"""
Get the converter for data that has the same type as *x*. If no
converters are registered for *x*, returns ``None``.
"""

if not len(self):
return None # nothing registered
# DISABLED idx = id(x)
# DISABLED cached = self._cached.get(idx)
# DISABLED if cached is not None: return cached

converter = None
classx = getattr(x, '__class__', None)

if classx is not None:
converter = self.get(classx)

if converter is None and hasattr(x, "values"):
# this unpacks pandas series or dataframes...
x = x.values

# If x is an array, look inside the array for data with units
"""Get the converter interface instance for *x*, or None."""
if hasattr(x, "values"):
x = x.values # Unpack pandas Series and DataFrames.
if isinstance(x, np.ndarray):
# In case x in a masked array, access the underlying data (only its
# type matters). If x is a regular ndarray, getdata() just returns
# the array itself.
x = np.ma.getdata(x).ravel()
# If there are no elements in x, infer the units from its dtype
if not x.size:
return self.get_converter(np.array([0], dtype=x.dtype))
xravel = x.ravel()
try:
# pass the first value of x that is not masked back to
# get_converter
if not np.all(xravel.mask):
# Get first non-masked item
converter = self.get_converter(
xravel[np.argmin(xravel.mask)])
return converter
except AttributeError:
# not a masked_array
# Make sure we don't recurse forever -- it's possible for
# ndarray subclasses to continue to return subclasses and
# not ever return a non-subclass for a single element.
next_item = xravel[0]
if (not isinstance(next_item, np.ndarray) or
next_item.shape != x.shape):
converter = self.get_converter(next_item)
return converter

# If we haven't found a converter yet, try to get the first element
if converter is None:
try:
thisx = cbook.safe_first_element(x)
try: # Look up in the cache.
return self[type(x)]
except KeyError:
try: # If cache lookup fails, look up based on first element...
first = cbook.safe_first_element(x)
except (TypeError, StopIteration):
pass
else:
if classx and classx != getattr(thisx, '__class__', None):
converter = self.get_converter(thisx)
return converter

# DISABLED self._cached[idx] = converter
return converter
# ... and avoid infinite recursion for pathological iterables
# where indexing returns instances of the same iterable class.
if type(first) is not type(x):
return self.get_converter(first)
return None


registry = Registry()