Use AutoFormatter for deglat/lon/etc., improve AutoFormatter log-scale patch

Author: lukelbd

CHANGELOG.rst

@@ -60,6 +60,24 @@ ProPlot v0.3.0 (2020-01-##)
   with a default ``.proplotrc`` file, change the auto-generated user ``.proplotrc``
   (:pr:`50`).
 
+ProPlot v0.2.6 (2019-12-09)
+===========================
+
+.. rubric:: Bug fixes
+
+- Fix issue where `~proplot.styletools.AutoFormatter` logarithmic scale
+  points are incorrect (:commit:`9b164733`).
+
+.. rubric:: Internals
+
+- Remove `prefix`, `suffix`, and `negpos` keyword args from
+  `~proplot.styletools.SimpleFormatter`, remove `precision` keyword arg from
+  `~proplot.styletools.AutoFormatter` (it automatically figures out the
+  necessary precision!).
+- Make ``'deglat'``, ``'deglon'``, ``'lat'``, ``'lon'``, and ``'deg'`` instances
+  of `~proplot.styletools.AutoFormatter` instead of `~proplot.styletools.SimpleFormatter`.
+  The latter should just be used for contours.
+
 ProPlot v0.2.6 (2019-12-08)
 ===========================
 .. rubric:: Bug fixes

docs/axis.ipynb

@@ -84,6 +84,15 @@
     "ProPlot lets you easily change the axis formatter with `~proplot.axes.Axes.format` (keyword args `xformatter` and `yformatter`, or their aliases `xticklabels` and `yticklabels`). The builtin matplotlib formatters can be referenced by string name, and several new formatters have been introduced -- for example, you can now easily label your axes as fractions or as geographic coordinates. You can also just pass a list of strings or a ``%`` style format directive. See `~proplot.axes.XYAxes.format` and `~proplot.axistools.Formatter` for details."
    ]
   },
+  {
+   "cell_type": "raw",
+   "metadata": {
+    "raw_mimetype": "text/restructuredtext"
+   },
+   "source": [
+    "ProPlot also changes the default axis formatter. The new formatter trims trailing zeros by default, and can be used to *filter tick labels within some data range*, as demonstrated below. See `~proplot.axistools.AutoFormatter` for details."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -109,15 +118,6 @@
     "plot.rc.reset()"
    ]
   },
-  {
-   "cell_type": "raw",
-   "metadata": {
-    "raw_mimetype": "text/restructuredtext"
-   },
-   "source": [
-    "ProPlot also changes the default axis formatter. The new formatter trims trailing zeros by default, and can be used to *filter tick labels within some data range*, as demonstrated below. See `~proplot.axistools.AutoFormatter` for details."
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -155,8 +155,8 @@
     "raw_mimetype": "text/restructuredtext"
    },
    "source": [
-    "The axis scale can now be changed with `~proplot.axes.Axes.format` (keyword args `xscale` and `yscale`). You can also configure the ``'log'`` and ``'symlog'`` axis scales with the more sensible `base`, `linthresh`, `linscale`, and `subs`\n",
-    "keyword args (i.e. you can omit the ``x`` and ``y``). See `~proplot.axes.XYAxes.format`, `~proplot.axistools.Scale`, `~proplot.axistools.LogScale` and `~proplot.axistools.SymmetricalLogScale` for details."
+    "The axis scale can now be changed with `~proplot.axes.Axes.format` (keyword args `xscale` and `yscale`). You can now configure the ``'log'`` and ``'symlog'`` axis scales with the more sensible `base`, `linthresh`, `linscale`, and `subs`\n",
+    "keyword args, rather than ``basex``, ``basey``, etc. Also, ProPlot's `~proplot.axistools.AutoFormatter` formatter is used for all axis scales by default; this can be changed e.g. by passing ``yformatter='log'`` to `~proplot.axes.XYAxes.format`. See `~proplot.axistools.Scale`, `~proplot.axistools.LogScale` and `~proplot.axistools.SymmetricalLogScale` for details."
    ]
   },
   {
@@ -201,7 +201,7 @@
     "raw_mimetype": "text/restructuredtext"
    },
    "source": [
-    "ProPlot also adds several new axis scales. The ``'cutoff'`` scale is great when you have weirdly distributed data (see `~proplot.axistools.CutoffScale`). The ``'sine'`` scale scales the axis as the sine of the coordinate, resulting in an \"area-weighted\" spherical latitude coordinate, and the ``'Mercator'`` scale scales the axis as with the Mercator projection latitude coordinate. The ``'inverse'`` scale is perfect for working with spectral data (this is more useful with `~proplot.axes.XYAxes.dualx` and `~proplot.axes.XYAxes.dualy`; see :ref:`Dual unit axes`)."
+    "ProPlot adds several new axis scales. The ``'cutoff'`` scale is great when you have weirdly distributed data (see `~proplot.axistools.CutoffScale`). The ``'sine'`` scale scales the axis as the sine of the coordinate, resulting in an \"area-weighted\" spherical latitude coordinate, and the ``'Mercator'`` scale scales the axis as with the Mercator projection latitude coordinate. The ``'inverse'`` scale is perfect for working with spectral data (this is more useful with `~proplot.axes.XYAxes.dualx` and `~proplot.axes.XYAxes.dualy`; see :ref:`Dual unit axes`)."
    ]
   },
   {

proplot/axistools.py

@@ -30,7 +30,7 @@
     'SymmetricalLogScale',
 ]
 
-# Scale preset names and positional args
+MAX_DIGITS = 32  # do not draw 1000 digits when LogScale limits include zero!
 SCALE_PRESETS = {
     'quadratic': ('power', 2,),
     'cubic': ('power', 3,),
@@ -194,11 +194,11 @@ def Formatter(formatter, *args, date=False, index=False, **kwargs):
         ``'theta'``             `~matplotlib.projections.polar.ThetaFormatter`  Formats radians as degrees, with a degree symbol
         ``'pi'``                `FracFormatter` preset                          Fractions of :math:`\\pi`
         ``'e'``                 `FracFormatter` preset                          Fractions of *e*
-        ``'deg'``               `SimpleFormatter` preset                        Trailing degree symbol
-        ``'deglon'``            `SimpleFormatter` preset                        Trailing degree symbol and cardinal "WE" indicator
-        ``'deglat'``            `SimpleFormatter` preset                        Trailing degree symbol and cardinal "SN" indicator
-        ``'lon'``               `SimpleFormatter` preset                        Cardinal "WE" indicator
-        ``'lat'``               `SimpleFormatter` preset                        Cardinal "SN" indicator
+        ``'deg'``               `AutoFormatter` preset                          Trailing degree symbol
+        ``'deglon'``            `AutoFormatter` preset                          Trailing degree symbol and cardinal "WE" indicator
+        ``'deglat'``            `AutoFormatter` preset                          Trailing degree symbol and cardinal "SN" indicator
+        ``'lon'``               `AutoFormatter` preset                          Cardinal "WE" indicator
+        ``'lat'``               `AutoFormatter` preset                          Cardinal "SN" indicator
         ======================  ==============================================  ===================================================================================================================================
 
     date : bool, optional
@@ -255,7 +255,7 @@ def Formatter(formatter, *args, date=False, index=False, **kwargs):
                     negpos = 'WE'
                 kwargs.setdefault('suffix', suffix)
                 kwargs.setdefault('negpos', negpos)
-                formatter = 'simple'
+                formatter = 'auto'
             # Lookup
             if formatter not in formatters:
                 raise ValueError(
@@ -348,6 +348,15 @@ def Scale(scale, *args, **kwargs):
     return scale(*args, **kwargs)
 
 
+def _zerofix(x, string, precision=6):
+    """
+    Try to fix non-zero tick labels formatted as ``'0'``.
+    """
+    if string.rstrip('0').rstrip('.') == '0' and x != 0:
+        string = ('{:.%df}' % precision).format(x)
+    return string
+
+
 class AutoFormatter(mticker.ScalarFormatter):
     """
     The new default formatter, a simple wrapper around
@@ -362,30 +371,40 @@ class AutoFormatter(mticker.ScalarFormatter):
     """
     def __init__(self, *args,
                  zerotrim=None, precision=None, tickrange=None,
-                 prefix=None, suffix=None, **kwargs):
+                 prefix=None, suffix=None, negpos=None, **kwargs):
         """
         Parameters
         ----------
         zerotrim : bool, optional
             Whether to trim trailing zeros.
             Default is :rc:`axes.formatter.zerotrim`.
-        precision : float, optional
-            The maximum number of digits after the decimal point.
         tickrange : (float, float), optional
             Range within which major tick marks are labelled.
         prefix, suffix : str, optional
-            Optional prefix and suffix for all strings.
+            Prefix and suffix for all strings.
+        negpos : str, optional
+            Length-2 string indicating the suffix for "negative" and "positive"
+            numbers, meant to replace the minus sign. This is useful for
+            indicating cardinal geographic coordinates.
         *args, **kwargs
-            Passed to `matplotlib.ticker.ScalarFormatter`.
+            Passed to `~matplotlib.ticker.ScalarFormatter`.
+
+        Warning
+        -------
+        The matplotlib `~matplotlib.ticker.ScalarFormatter` determines the
+        number of significant digits based on the axis limits, and therefore
+        may *truncate* digits while formatting ticks on highly non-linear
+        axis scales like `~proplot.axistools.LogScale`. We try to correct
+        this behavior with a patch.
         """
         tickrange = tickrange or (-np.inf, np.inf)
         super().__init__(*args, **kwargs)
         zerotrim = _notNone(zerotrim, rc.get('axes.formatter.zerotrim'))
-        self._maxprecision = precision
         self._zerotrim = zerotrim
         self._tickrange = tickrange
         self._prefix = prefix or ''
         self._suffix = suffix or ''
+        self._negpos = negpos or ''
 
     def __call__(self, x, pos=None):
         """
@@ -403,75 +422,62 @@ def __call__(self, x, pos=None):
         tickrange = self._tickrange
         if (x + eps) < tickrange[0] or (x - eps) > tickrange[1]:
             return ''  # avoid some ticks
-        # Normal formatting
+        # Negative positive handling
+        if not self._negpos:
+            tail = ''
+        elif x > 0:
+            tail = self._negpos[1]
+        else:
+            x *= -1
+            tail = self._negpos[0]
+        # Format the string
         string = super().__call__(x, pos)
-        if string == '0' and x != 0:  # weird LogScale issue
-            string = ('{:.%df}' % (self._maxprecision or 6)).format(x)
-        if self._maxprecision is not None and '.' in string:
-            head, tail = string.split('.')
-            string = head + '.' + tail[:self._maxprecision]
-        if self._zerotrim and '.' in string:
-            string = string.rstrip('0').rstrip('.')
-        if string == '-0' or string == '\N{MINUS SIGN}0':
-            string = '0'
+        for i in range(2):
+            # Try to fix non-zero values formatted as zero
+            if self._zerotrim and '.' in string:
+                string = string.rstrip('0').rstrip('.')
+            if string == '-0' or string == '\N{MINUS SIGN}0':
+                string = '0'
+            if i == 0 and string == '0' and x != 0:
+                # Hard limit of 10 sigfigs
+                string = ('{:.%df}' % min(
+                    abs(np.log10(x) // 1), MAX_DIGITS)).format(x)
+                continue
+            break
         # Prefix and suffix
         sign = ''
         string = string.replace('-', '\N{MINUS SIGN}')
         if string and string[0] == '\N{MINUS SIGN}':
             sign, string = string[0], string[1:]
-        # if 0 < x < 1:
-        #     print(x, repr(string))
-        return sign + self._prefix + string + self._suffix
+        if tail:
+            sign = ''
+        return sign + self._prefix + string + self._suffix + tail
 
 
-def SimpleFormatter(*args, precision=6,
-                    prefix=None, suffix=None, negpos=None, zerotrim=True,
-                    **kwargs):
+def SimpleFormatter(*args, precision=6, zerotrim=True, **kwargs):
     """
-    Replicates features of `AutoFormatter`, but as a simpler
+    Replicates the `zerotrim` feature from `AutoFormatter`, but as a simpler
     `~matplotlib.ticker.FuncFormatter` instance. This is more suitable for
     arbitrary number formatting not necessarily associated with any
-    `~matplotlib.axis.Axis` instance, e.g. labelling contours.
+    `~matplotlib.axis.Axis` instance, e.g. labeling contours.
 
     Parameters
     ----------
     precision : int, optional
-        Maximum number of digits after the decimal point.
-    prefix, suffix : str, optional
-        Optional prefix and suffix for all strings.
-    negpos : str, optional
-        Length-2 string that indicates suffix for "negative" and "positive"
-        numbers, meant to replace the minus sign. This is useful for
-        indicating cardinal geographic coordinates.
+        The maximum number of digits after the decimal point.
     zerotrim : bool, optional
         Whether to trim trailing zeros.
         Default is :rc:`axes.formatter.zerotrim`.
     """
-    prefix = prefix or ''
-    suffix = suffix or ''
     zerotrim = _notNone(zerotrim, rc['axes.formatter.zerotrim'])
 
     def f(x, pos):
-        # Apply suffix if not on equator/prime meridian
-        if not negpos:
-            tail = ''
-        elif x > 0:
-            tail = negpos[1]
-        else:
-            x *= -1
-            tail = negpos[0]
-        # Finally use default formatter
         string = ('{:.%df}' % precision).format(x)
         if zerotrim and '.' in string:
             string = string.rstrip('0').rstrip('.')
         if string == '-0' or string == '\N{MINUS SIGN}0':
             string = '0'
-        # Prefix and suffix
-        sign = ''
-        string = string.replace('-', '\N{MINUS SIGN}')
-        if string and string[0] == '\N{MINUS SIGN}':
-            sign, string = string[0], string[1:]
-        return sign + prefix + string + suffix + tail
+        return string.replace('-', '\N{MINUS SIGN}')
     return mticker.FuncFormatter(f)