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Add public method to update Legend object's loc property . #26089

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Merged
merged 1 commit into from
Jun 16, 2023
Merged

Add public method to update Legend object's loc property . #26089

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23 changes: 23 additions & 0 deletions doc/users/next_whats_new/set_loc.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
Add a public method to modify the location of ``Legend``
--------------------------------------------------------

`~matplotlib.legend.Legend` locations now can be tweaked after they've been defined.

.. plot::
:include-source: true

from matplotlib import pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(1, 1, 1)

x = list(range(-100, 101))
y = [i**2 for i in x]

ax.plot(x, y, label="f(x)")
ax.legend()
ax.get_legend().set_loc("right")
# Or
# ax.get_legend().set(loc="right")

plt.show()
130 changes: 75 additions & 55 deletions lib/matplotlib/legend.py
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Original file line number Diff line number Diff line change
Expand Up @@ -330,6 +330,12 @@ def _update_bbox_to_anchor(self, loc_in_canvas):
_legend_kw_doc_base)
_docstring.interpd.update(_legend_kw_doc=_legend_kw_both_st)

_legend_kw_set_loc_st = (
_loc_doc_base.format(parent='axes/figure',
default=":rc:`legend.loc` for Axes, 'upper right' for Figure",
best=_loc_doc_best, outside=_outside_doc))
_docstring.interpd.update(_legend_kw_set_loc_doc=_legend_kw_set_loc_st)


class Legend(Artist):
"""
Expand Down Expand Up @@ -503,58 +509,6 @@ def val_or_rc(val, rc_name):
)
self.parent = parent

loc0 = loc
self._loc_used_default = loc is None
if loc is None:
loc = mpl.rcParams["legend.loc"]
if not self.isaxes and loc in [0, 'best']:
loc = 'upper right'

type_err_message = ("loc must be string, coordinate tuple, or"
f" an integer 0-10, not {loc!r}")

# handle outside legends:
self._outside_loc = None
if isinstance(loc, str):
if loc.split()[0] == 'outside':
# strip outside:
loc = loc.split('outside ')[1]
# strip "center" at the beginning
self._outside_loc = loc.replace('center ', '')
# strip first
self._outside_loc = self._outside_loc.split()[0]
locs = loc.split()
if len(locs) > 1 and locs[0] in ('right', 'left'):
# locs doesn't accept "left upper", etc, so swap
if locs[0] != 'center':
locs = locs[::-1]
loc = locs[0] + ' ' + locs[1]
# check that loc is in acceptable strings
loc = _api.check_getitem(self.codes, loc=loc)
elif np.iterable(loc):
# coerce iterable into tuple
loc = tuple(loc)
# validate the tuple represents Real coordinates
if len(loc) != 2 or not all(isinstance(e, numbers.Real) for e in loc):
raise ValueError(type_err_message)
elif isinstance(loc, int):
# validate the integer represents a string numeric value
if loc < 0 or loc > 10:
raise ValueError(type_err_message)
else:
# all other cases are invalid values of loc
raise ValueError(type_err_message)

if self.isaxes and self._outside_loc:
raise ValueError(
f"'outside' option for loc='{loc0}' keyword argument only "
"works for figure legends")

if not self.isaxes and loc == 0:
raise ValueError(
"Automatic legend placement (loc='best') not implemented for "
"figure legend")

self._mode = mode
self.set_bbox_to_anchor(bbox_to_anchor, bbox_transform)

Expand Down Expand Up @@ -598,9 +552,8 @@ def val_or_rc(val, rc_name):
# init with null renderer
self._init_legend_box(handles, labels, markerfirst)

tmp = self._loc_used_default
self._set_loc(loc)
self._loc_used_default = tmp # ignore changes done by _set_loc
# Set legend location
self.set_loc(loc)

# figure out title font properties:
if title_fontsize is not None and title_fontproperties is not None:
Expand Down Expand Up @@ -686,6 +639,73 @@ def _set_artist_props(self, a):

a.set_transform(self.get_transform())

@_docstring.dedent_interpd
def set_loc(self, loc=None):
"""
Set the location of the legend.

.. versionadded:: 3.8

Parameters
----------
%(_legend_kw_set_loc_doc)s
"""
loc0 = loc
self._loc_used_default = loc is None
if loc is None:
loc = mpl.rcParams["legend.loc"]
if not self.isaxes and loc in [0, 'best']:
loc = 'upper right'

type_err_message = ("loc must be string, coordinate tuple, or"
f" an integer 0-10, not {loc!r}")

# handle outside legends:
self._outside_loc = None
if isinstance(loc, str):
if loc.split()[0] == 'outside':
# strip outside:
loc = loc.split('outside ')[1]
# strip "center" at the beginning
self._outside_loc = loc.replace('center ', '')
# strip first
self._outside_loc = self._outside_loc.split()[0]
locs = loc.split()
if len(locs) > 1 and locs[0] in ('right', 'left'):
# locs doesn't accept "left upper", etc, so swap
if locs[0] != 'center':
locs = locs[::-1]
loc = locs[0] + ' ' + locs[1]
# check that loc is in acceptable strings
loc = _api.check_getitem(self.codes, loc=loc)
elif np.iterable(loc):
# coerce iterable into tuple
loc = tuple(loc)
# validate the tuple represents Real coordinates
if len(loc) != 2 or not all(isinstance(e, numbers.Real) for e in loc):
raise ValueError(type_err_message)
elif isinstance(loc, int):
# validate the integer represents a string numeric value
if loc < 0 or loc > 10:
raise ValueError(type_err_message)
else:
# all other cases are invalid values of loc
raise ValueError(type_err_message)

if self.isaxes and self._outside_loc:
raise ValueError(
f"'outside' option for loc='{loc0}' keyword argument only "
"works for figure legends")

if not self.isaxes and loc == 0:
raise ValueError(
"Automatic legend placement (loc='best') not implemented for "
"figure legend")

tmp = self._loc_used_default
self._set_loc(loc)
self._loc_used_default = tmp # ignore changes done by _set_loc

def _set_loc(self, loc):
# find_offset function will be provided to _legend_box and
# _legend_box will draw itself at the location of the return
Expand Down
1 change: 1 addition & 0 deletions lib/matplotlib/legend.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,7 @@ class Legend(Artist):
def get_texts(self) -> list[Text]: ...
def set_alignment(self, alignment: Literal["center", "left", "right"]) -> None: ...
def get_alignment(self) -> Literal["center", "left", "right"]: ...
def set_loc(self, loc: str | tuple[float, float] | int | None = ...) -> None: ...
def set_title(
self, title: str, prop: FontProperties | str | pathlib.Path | None = ...
) -> None: ...
Expand Down
20 changes: 20 additions & 0 deletions lib/matplotlib/tests/test_legend.py
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Original file line number Diff line number Diff line change
Expand Up @@ -755,6 +755,26 @@ def test_legend_alignment(alignment):
assert leg.get_alignment() == alignment


@pytest.mark.parametrize('loc', ('center', 'best',))
def test_ax_legend_set_loc(loc):
fig, ax = plt.subplots()
ax.plot(range(10), label='test')
leg = ax.legend()
leg.set_loc(loc)
assert leg._get_loc() == mlegend.Legend.codes[loc]


@pytest.mark.parametrize('loc', ('outside right', 'right',))
def test_fig_legend_set_loc(loc):
fig, ax = plt.subplots()
ax.plot(range(10), label='test')
leg = fig.legend()
leg.set_loc(loc)

loc = loc.split()[1] if loc.startswith("outside") else loc
assert leg._get_loc() == mlegend.Legend.codes[loc]


@pytest.mark.parametrize('alignment', ('center', 'left', 'right'))
def test_legend_set_alignment(alignment):
fig, ax = plt.subplots()
Expand Down