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Use (sym)log locator / formatter for symlog scales by default
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@mwaskom
mwaskom committed Jun 26, 2022
1 parent fe3e338 commit 87d450f
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Showing 2 changed files with 84 additions and 28 deletions.
101 changes: 73 additions & 28 deletions seaborn/_core/scales.py
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
FixedLocator,
LinearLocator,
LogLocator,
SymmetricalLogLocator,
MaxNLocator,
MultipleLocator,
EngFormatter,
Expand Down Expand Up @@ -222,16 +223,48 @@ def spacer(x):

return new

def tick(self, locator=None):
def tick(self, locator: Locator | None = None):
"""
Configure the selection of ticks for the scale's axis or legend.
.. note::
This API is under construction and will be enhanced over time.
At the moment, it is probably not very useful.
Parameters
----------
locator: :class:`matplotlib.ticker.Locator` subclass
Pre-configured matplotlib locator; other parameters will not be used.
Returns
-------
Copy of self with new tick configuration.
"""
new = copy(self)
new._tick_params = {
"locator": locator,
}
return new

def label(self, formatter=None):
def label(self, formatter: Formatter | None = None):
"""
Configure the selection of labels for the scale's axis or legend.
.. note::
This API is under construction and will be enhanced over time.
At the moment, it is probably not very useful.
Parameters
----------
formatter: :class:`matplotlib.ticker.Formatter` subclass
Pre-configured matplotlib formatter; other parameters will not be used.
Returns
-------
Copy of self with new tick configuration.
"""
new = copy(self)
new._label_params = {
"formatter": formatter,
Expand Down Expand Up @@ -396,7 +429,7 @@ def tick(
Parameters
----------
locator: matplotlib Locator
locator: :class:`matplotlib.ticker.Locator` subclass
Pre-configured matplotlib locator; other parameters will not be used.
at : sequence of floats
Place ticks at these specific locations (in data units).
Expand Down Expand Up @@ -452,7 +485,7 @@ def tick(

def label(
self,
formatter=None, *,
formatter: Formatter | None = None, *,
like: str | Callable | None = None,
base: int | None = None,
unit: str | None = None,
Expand All @@ -462,7 +495,7 @@ def label(
Parameters
----------
formatter : matplotlib Formatter
formatter: :class:`matplotlib.ticker.Formatter` subclass
Pre-configured formatter to use; other parameters will be ignored.
like : str or callable
Either a format pattern (e.g., `".2f"`), a format string with fields named
Expand Down Expand Up @@ -499,25 +532,29 @@ def label(
}
return new

def _parse_for_log_params(self, transform):

log_base = symlog_thresh = None
if isinstance(transform, str):
m = re.match(r"^log(\d*)", transform)
if m is not None:
log_base = float(m[1] or 10)
m = re.match(r"symlog(\d*)", transform)
if m is not None:
symlog_thresh = float(m[1] or 1)
return log_base, symlog_thresh

def _get_locators(self, locator, at, upto, count, every, between, minor):

# TODO what about symlog?
if isinstance(self.transform, str):
m = re.match(r"log(\d*)", self.transform)
log_transform = m is not None
log_base = m[1] or 10 if m is not None else None
forward, inverse = self._get_transform()
else:
log_transform = False
log_base = forward = inverse = None
log_base, symlog_thresh = self._parse_for_log_params(self.transform)

if locator is not None:
major_locator = locator

# TODO raise if locator is passed with any other parameters

elif upto is not None:
if log_transform:
if log_base:
major_locator = LogLocator(base=log_base, numticks=upto)
else:
major_locator = MaxNLocator(upto, steps=[1, 1.5, 2, 2.5, 3, 5, 10])
Expand All @@ -527,7 +564,8 @@ def _get_locators(self, locator, at, upto, count, every, between, minor):
# This is rarely useful (unless you are setting limits)
major_locator = LinearLocator(count)
else:
if log_transform:
if log_base or symlog_thresh:
forward, inverse = self._get_transform()
lo, hi = forward(between)
ticks = inverse(np.linspace(lo, hi, num=count))
else:
Expand All @@ -546,12 +584,17 @@ def _get_locators(self, locator, at, upto, count, every, between, minor):
major_locator = FixedLocator(at)

else:
major_locator = LogLocator(log_base) if log_transform else AutoLocator()
if log_base:
major_locator = LogLocator(log_base)
elif symlog_thresh:
major_locator = SymmetricalLogLocator(linthresh=symlog_thresh, base=10)
else:
major_locator = AutoLocator()

if minor is None:
minor_locator = LogLocator(log_base, subs=None) if log_transform else None
minor_locator = LogLocator(log_base, subs=None) if log_base else None
else:
if log_transform:
if log_base:
subs = np.linspace(0, log_base, minor + 2)[1:-1]
minor_locator = LogLocator(log_base, subs=subs)
else:
Expand All @@ -561,11 +604,11 @@ def _get_locators(self, locator, at, upto, count, every, between, minor):

def _get_formatter(self, locator, formatter, like, base, unit):

# TODO this has now been copied in a few places
if base is None and isinstance(self.transform, str):
# TODO handle symlog too
m = re.match(r"log(\d*)", self.transform)
base = m[1] or 10 if m is not None else None
log_base, symlog_thresh = self._parse_for_log_params(self.transform)
if base is None:
if symlog_thresh:
log_base = 10
base = log_base

if formatter is not None:
return formatter
Expand Down Expand Up @@ -623,11 +666,12 @@ def tick(
"""
Configure the selection of ticks for the scale's axis or legend.
This API is under construction and will be enhanced over time.
.. note::
This API is under construction and will be enhanced over time.
Parameters
----------
locator: matplotlib Locator
locator: :class:`matplotlib.ticker.Locator` subclass
Pre-configured matplotlib locator; other parameters will not be used.
upto : int
Choose "nice" locations for ticks, but do not exceed this number.
Expand Down Expand Up @@ -656,11 +700,12 @@ def label(
"""
Configure the appearance of tick labels for the scale's axis or legend.
This API is under construction and will be enhanced over time.
.. note::
This API is under construction and will be enhanced over time.
Parameters
----------
formatter : matplotlib Formatter
formatter: :class:`matplotlib.ticker.Formatter` subclass
Pre-configured formatter to use; other parameters will be ignored.
concise : bool
If True, use :class:`matplotlib.dates.ConciseDateFormatter` to make
Expand Down
11 changes: 11 additions & 0 deletions tests/_core/test_scales.py
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Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,17 @@ def test_log_tick_every(self, x):
with pytest.raises(RuntimeError, match="`every` not supported"):
Continuous(transform="log").tick(every=2)

def test_symlog_tick_default(self, x):

s = Continuous(transform="symlog")._setup(x, Coordinate())
a = PseudoAxis(s._matplotlib_scale)
a.set_view_interval(-1050, 1050)
ticks = a.major.locator()
assert ticks[0] == -ticks[-1]
pos_ticks = np.sort(np.unique(np.abs(ticks)))
assert np.allclose(np.diff(np.log10(pos_ticks[1:])), 1)
assert pos_ticks[0] == 0

def test_label_formatter(self, x):

fmt = mpl.ticker.FormatStrFormatter("%.3f")
Expand Down

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