Automatically create tick formatters for str and callable inputs. · matplotlib/matplotlib@e07c5df · GitHub
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Automatically create tick formatters for str and callable inputs.
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Lines changed: 112 additions & 34 deletions

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‎doc/users/next_whats_new/2020-03-06-auto-tick-formatters.rst‎

Lines changed: 7 additions & 0 deletions

‎examples/ticks_and_spines/tick-formatters.py‎

Lines changed: 20 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -34,7 +34,7 @@ def setup(ax, title):
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fontsize=14, fontname='Monospace', color='tab:blue')
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3636

37-
fig, axs = plt.subplots(7, 1, figsize=(8, 6))
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fig, axs = plt.subplots(9, 1, figsize=(8, 8))
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# Null formatter
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setup(axs[0], title="NullFormatter()")
@@ -59,21 +59,30 @@ def major_formatter(x, pos):
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setup(axs[2], title='FuncFormatter(lambda x, pos: "[%.2f]" % x)')
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axs[2].xaxis.set_major_formatter(major_formatter)
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62-
# FormatStr formatter
63-
setup(axs[3], title="FormatStrFormatter('#%d')")
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axs[3].xaxis.set_major_formatter(ticker.FormatStrFormatter("#%d"))
62+
# FuncFormatter can be automatically created directly with a function input
63+
# without needing to manually create the formatter
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setup(axs[3], title="lambda x, pos: str(x-5)")
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axs[3].xaxis.set_major_formatter(lambda x, pos: str(x-5))
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# StrMethod formatter
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setup(axs[4], title="StrMethodFormatter('{x:.3f}')")
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axs[4].xaxis.set_major_formatter(ticker.StrMethodFormatter("{x:.3f}"))
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# StrMethodFormatter can also be created directly with a string input.
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setup(axs[5], title="'{x} km'")
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axs[5].xaxis.set_major_formatter('{x} km')
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# Scalar formatter
67-
setup(axs[4], title="ScalarFormatter()")
68-
axs[4].xaxis.set_major_formatter(ticker.ScalarFormatter(useMathText=True))
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setup(axs[6], title="ScalarFormatter()")
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axs[6].xaxis.set_major_formatter(ticker.ScalarFormatter(useMathText=True))
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70-
# StrMethod formatter
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setup(axs[5], title="StrMethodFormatter('{x:.3f}')")
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axs[5].xaxis.set_major_formatter(ticker.StrMethodFormatter("{x:.3f}"))
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# FormatStr formatter
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setup(axs[7], title="FormatStrFormatter('#%d')")
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axs[7].xaxis.set_major_formatter(ticker.FormatStrFormatter("#%d"))
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# Percent formatter
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setup(axs[6], title="PercentFormatter(xmax=5)")
76-
axs[6].xaxis.set_major_formatter(ticker.PercentFormatter(xmax=5))
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setup(axs[8], title="PercentFormatter(xmax=5)")
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axs[8].xaxis.set_major_formatter(ticker.PercentFormatter(xmax=5))
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plt.tight_layout()
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plt.show()

‎lib/matplotlib/axis.py‎

Lines changed: 47 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -1529,37 +1529,68 @@ def set_major_formatter(self, formatter):
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"""
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Set the formatter of the major ticker.
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1532+
In addition to a `~matplotlib.ticker.Formatter` instance,
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this also accepts a `str` or function.
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For a `str` a `~matplotlib.ticker.StrMethodFormatter` is used.
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For a function a `~matplotlib.ticker.FuncFormatter` is used.
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Parameters
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----------
1534-
formatter : `~matplotlib.ticker.Formatter`
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formatter : `~matplotlib.ticker.Formatter`, str, or function
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"""
1536-
cbook._check_isinstance(mticker.Formatter, formatter=formatter)
1537-
if (isinstance(formatter, mticker.FixedFormatter)
1538-
and len(formatter.seq) > 0
1539-
and not isinstance(self.major.locator, mticker.FixedLocator)):
1540-
cbook._warn_external('FixedFormatter should only be used together '
1541-
'with FixedLocator')
1542-
self.isDefault_majfmt = False
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self.major.formatter = formatter
1544-
formatter.set_axis(self)
1545-
self.stale = True
1541+
self._set_formatter(formatter, self.major)
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15471543
def set_minor_formatter(self, formatter):
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"""
15491545
Set the formatter of the minor ticker.
15501546
1547+
In addition to a `~matplotlib.ticker.Formatter` instance,
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this also accepts a `str` or function.
1549+
For a `str` a `~matplotlib.ticker.StrMethodFormatter` is used.
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For a function a `~matplotlib.ticker.FuncFormatter` is used.
1551+
15511552
Parameters
15521553
----------
1553-
formatter : `~matplotlib.ticker.Formatter`
1554+
formatter : `~matplotlib.ticker.Formatter`, str, or function
1555+
"""
1556+
self._set_formatter(formatter, self.minor)
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1558+
def _set_formatter(self, formatter, level):
15541559
"""
1555-
cbook._check_isinstance(mticker.Formatter, formatter=formatter)
1560+
Set the formatter of the major or minor ticker.
1561+
1562+
In addition to a `~matplotlib.ticker.Formatter` instance,
1563+
this also accepts a `str` or function.
1564+
For a `str` a `~matplotlib.ticker.StrMethodFormatter` is used.
1565+
For a function a `~matplotlib.ticker.FuncFormatter` is used.
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1567+
Parameters
1568+
----------
1569+
formatter : `~matplotlib.ticker.Formatter`, str, or function
1570+
level : `self.major` or `self.minor`
1571+
"""
1572+
if isinstance(formatter, str):
1573+
formatter = mticker.StrMethodFormatter(formatter)
1574+
# Don't allow any other TickHelper to avoid easy-to-make errors,
1575+
# like using a Locator instead of a Formatter.
1576+
elif (callable(formatter) and
1577+
not isinstance(formatter, mticker.TickHelper)):
1578+
formatter = mticker.FuncFormatter(formatter)
1579+
else:
1580+
cbook._check_isinstance(mticker.Formatter, formatter=formatter)
1581+
15561582
if (isinstance(formatter, mticker.FixedFormatter)
15571583
and len(formatter.seq) > 0
1558-
and not isinstance(self.minor.locator, mticker.FixedLocator)):
1584+
and not isinstance(level.locator, mticker.FixedLocator)):
15591585
cbook._warn_external('FixedFormatter should only be used together '
15601586
'with FixedLocator')
1561-
self.isDefault_minfmt = False
1562-
self.minor.formatter = formatter
1587+
1588+
if level == self.major:
1589+
self.isDefault_majfmt = False
1590+
else:
1591+
self.isDefault_minfmt = False
1592+
1593+
level.formatter = formatter
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formatter.set_axis(self)
15641595
self.stale = True
15651596

‎lib/matplotlib/tests/test_axes.py‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -203,6 +203,28 @@ def test_formatter_ticker():
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ax.autoscale_view()
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205205

206+
def test_auto_formatter():
207+
def _formfunc(x, pos):
208+
return ''
209+
210+
formstr = '{x}_{pos}'
211+
212+
ax = plt.figure().subplots()
213+
ax.xaxis.set_major_formatter(_formfunc)
214+
ax.yaxis.set_minor_formatter(formstr)
215+
216+
targ_funcformatter = mticker.FuncFormatter(_formfunc)
217+
targ_strformatter = mticker.StrMethodFormatter(formstr)
218+
219+
assert isinstance(ax.xaxis.get_major_formatter(),
220+
mticker.FuncFormatter)
221+
assert isinstance(ax.yaxis.get_minor_formatter(),
222+
mticker.StrMethodFormatter)
223+
224+
assert ax.xaxis.get_major_formatter().func == targ_funcformatter.func
225+
assert ax.yaxis.get_minor_formatter().fmt == targ_strformatter.fmt
226+
227+
206228
@image_comparison(["twin_axis_locators_formatters"])
207229
def test_twin_axis_locators_formatters():
208230
vals = np.linspace(0, 1, num=5, endpoint=True)

‎lib/matplotlib/ticker.py‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -159,6 +159,12 @@
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ax.yaxis.set_major_formatter(ymajor_formatter)
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ax.yaxis.set_minor_formatter(yminor_formatter)
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162+
For `.StrMethodFormatter`, `~.Axis.set_major_formatter` and
163+
`~.Axis.set_minor_formatter` accept a ``str``. In that case a
164+
`.StrMethodFormatter` will be automatically created and applied based on
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the given ``str``. Similalry, a `.FuncFormatter` will be automatically
166+
created and applied if a function is provided.
167+
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See :doc:`/gallery/ticks_and_spines/major_minor_demo` for an
163169
example of setting major and minor ticks. See the :mod:`matplotlib.dates`
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module for more information and examples of using date locators and formatters.

‎tutorials/text/text_intro.py‎

Lines changed: 10 additions & 7 deletions

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