8000 Simplify decade up- and down-rounding. · matplotlib/matplotlib@6ac5d20 · GitHub
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Simplify decade up- and down-rounding.
Instead of `decade_up` and `decade_down`, use more explicit `_decade_less`, `_decade_less_equal`, etc. which moreover also handle negative values (used by the symlog scale). Previously, `semilogx([.1, .1], [1, 2])` would autoscale the x-axis from a bit less than 0.1 to a bit more than 1, because 0.1 == 10**-1 so decade_down(0.1) would use `floor(-1) == -1` and return 0.1, while decade_up(0.1) would return 1. With this PR, `semilogx([.1, .1], [1, 2])` instead autoscales the x-axis from a bit less than 0.01 to a bit more than 1 (i.e. one decade on each side), which seems more logical.
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‎doc/api/next_api_changes/2019-02-13-AL.rst

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@@ -0,0 +1,9 @@
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Deprecations
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````````````
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``ticker.decade_up`` and ``ticker.decade_down`` are deprecated.
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Autoscaling changes
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```````````````````
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On log-axes where a single value is plotted at a "full" decade (1, 10, 100,
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etc.), the autoscaling now expands the axis symmetrically around that point,
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instead of adding a decade only to the right.

‎lib/matplotlib/ticker.py

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Original file line numberDiff line numberDiff line change
@@ -2058,6 +2058,7 @@ def view_limits(self, dmin, dmax):
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return dmin, dmax
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@cbook.deprecated("3.1")
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def decade_down(x, base=10):
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'floor x to the nearest lower decade'
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if x == 0.0:
@@ -2066,6 +2067,7 @@ def decade_down(x, base=10):
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return base ** lx
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@cbook.deprecated("3.1")
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def decade_up(x, base=10):
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'ceil x to the nearest higher decade'
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if x == 0.0:
@@ -2091,6 +2093,56 @@ def is_decade(x, base=10):
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return is_close_to_int(lx)
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20932095

2096+
def _decade_less_equal(x, base):
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"""
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Return the largest integer power of *base* that's less or equal to *x*.
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If *x* is negative, the exponent will be *greater*.
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"""
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return (x if x == 0 else
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-_decade_greater_equal(-x, base) if x < 0 else
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base ** np.floor(np.log(x) / np.log(base)))
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def _decade_greater_equal(x, base):
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"""
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Return the smallest integer power of *base* that's greater or equal to *x*.
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If *x* is negative, the exponent will be *smaller*.
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"""
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return (x if x == 0 else
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-_decade_less_equal(-x, base) if x < 0 else
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base ** np.ceil(np.log(x) / np.log(base)))
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def _decade_less(x, base):
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"""
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Return the smallest integer power of *base* that's less than *x*.
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If *x* is negative, the exponent will be *smaller*.
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"""
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if x < 0:
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return -_decade_greater(-x, base)
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less = _decade_less_equal(x, base)
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if less == x:
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less /= base
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return less
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def _decade_greater(x, base):
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"""
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Return the smallest integer power of *base* that's greater than *x*.
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If *x* is negative, the exponent will be *smaller*.
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"""
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if x < 0:
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return -_decade_less(-x, base)
2140+
greater = _decade_greater_equal(x, base)
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if greater == x:
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greater *= base
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return greater
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def is_close_to_int(x):
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return abs(x - np.round(x)) < 1e-10
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@@ -2272,10 +2324,8 @@ def view_limits(self, vmin, vmax):
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vmin = b ** (vmax - self.numdecs)
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if rcParams['axes.autolimit_mode'] == 'round_numbers':
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if not is_decade(vmin, self._base):
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vmin = decade_down(vmin, self._base)
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if not is_decade(vmax, self._base):
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vmax = decade_up(vmax, self._base)
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vmin = _decade_less_equal(vmin, self._base)
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vmax = _decade_greater_equal(vmax, self._base)
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return vmin, vmax
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@@ -2297,8 +2347,8 @@ def nonsingular(self, vmin, vmax):
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if vmin <= 0:
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vmin = minpos
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if vmin == vmax:
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vmin = decade_down(vmin, self._base)
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vmax = decade_up(vmax, self._base)
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vmin = _decade_less(vmin, self._base)
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vmax = _decade_greater(vmax, self._base)
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return vmin, vmax
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@@ -2452,24 +2502,11 @@ def view_limits(self, vmin, vmax):
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vmin, vmax = vmax, vmin
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if rcParams['axes.autolimit_mode'] == 'round_numbers':
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if not is_decade(abs(vmin), b):
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if vmin < 0:
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vmin = -decade_up(-vmin, b)
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else:
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vmin = decade_down(vmin, b)
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if not is_decade(abs(vmax), b):
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if vmax < 0:
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vmax = -decade_down(-vmax, b)
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else:
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vmax = decade_up(vmax, b)
2465-
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vmin = _decade_less_equal(vmin, b)
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vmax = _decade_greater_equal(vmax, b)
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if vmin == vmax:
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if vmin < 0:
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vmin = -decade_up(-vmin, b)
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vmax = -decade_down(-vmax, b)
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else:
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vmin = decade_down(vmin, b)
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vmax = decade_up(vmax, b)
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vmin = _decade_less(vmin, b)
2509+
vmax = _decade_greater(vmax, b)
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24742511
result = mtransforms.nonsingular(vmin, vmax)
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return result

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