matplotlib · timhoffm · Feb 14, 2019 · Jan 30, 2019
diff --git a/doc/api/next_api_changes/2018-01-28-AL.rst b/doc/api/next_api_changes/2018-01-28-AL.rst
@@ -4,8 +4,13 @@ New `Formatter.format_ticks` method
 The `Formatter` class gained a new `~Formatter.format_ticks` method, which
 takes the list of all tick locations as a single argument and returns the list
 of all formatted values.  It is called by the axis tick handling code and, by
-default, repeatedly calls `~Formatter.__call__`.
+default, first calls `~Formatter.set_locs` with all locations, then repeatedly
+calls `~Formatter.__call__` for each location.
 
-It is intended to be overridden by `Formatter` subclasses for which
-the formatting of a tick value depends on other tick values, such as
-`ConciseDateFormatter`.
+Tick-handling code in the codebase that previously performed this sequence
+(`~Formatter.set_locs` followed by repeated `~Formatter.__call__`) have been
+updated to use `~Formatter.format_ticks`.
+
+`~Formatter.format_ticks` is intended to be overridden by `Formatter`
+subclasses for which the formatting of a tick value depends on other tick
+values, such as `ConciseDateFormatter`.
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -934,12 +934,10 @@ def iter_ticks(self):
         """
         major_locs = self.major.locator()
         major_ticks = self.get_major_ticks(len(major_locs))
-        self.major.formatter.set_locs(major_locs)
         major_labels = self.major.formatter.format_ticks(major_locs)
 
         minor_locs = self.minor.locator()
         minor_ticks = self.get_minor_ticks(len(minor_locs))
-        self.minor.formatter.set_locs(minor_locs)
         minor_labels = self.minor.formatter.format_ticks(minor_locs)
 
         yield from zip(major_ticks, major_locs, major_labels)

diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -788,7 +788,6 @@ def _ticker(self, locator, formatter):
             b = b[(b <= intv[1] + eps) & (b >= intv[0] - eps)]
         self._manual_tick_data_values = b
         ticks = self._locate(b)
-        formatter.set_locs(b)
         ticklabels = formatter.format_ticks(b)
         offset_string = formatter.get_offset()
         return ticks, ticklabels, offset_string

diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -255,6 +255,7 @@ def __call__(self, x, pos=None):
 
     def format_ticks(self, values):
         """Return the tick labels for all the ticks at once."""
+        self.set_locs(values)
         return [self(value, i) for i, value in enumerate(values)]
 
     def format_data(self, value):

diff --git a/lib/mpl_toolkits/axisartist/axislines.py b/lib/mpl_toolkits/axisartist/axislines.py
@@ -225,12 +225,10 @@ def get_tick_iterators(self, axes):
 
             major = self.axis.major
             majorLocs = major.locator()
-            major.formatter.set_locs(majorLocs)
             majorLabels = major.formatter.format_ticks(majorLocs)
 
             minor = self.axis.minor
             minorLocs = minor.locator()
-            minor.formatter.set_locs(minorLocs)
             minorLabels = minor.formatter.format_ticks(minorLocs)
 
             trans_tick = self.get_tick_transform(axes)

diff --git a/lib/mpl_toolkits/axisartist/grid_finder.py b/lib/mpl_toolkits/axisartist/grid_finder.py
@@ -291,11 +291,9 @@ def __init__(self, useMathText=True):
     def __call__(self, direction, factor, values):
         if not self._ignore_factor:
             if factor is None:
-                factor = 1.
-            values = [v/factor for v in values]
-        #values = [v for v in values]
-        self._fmt.set_locs(values)
-        return [self._fmt(v) for v in values]
+                factor = 1
+            values = [v / factor for v in values]
+        return self._fmt.format_ticks(values)
 
 
 class DictFormatter(object):

diff --git a/lib/mpl_toolkits/mplot3d/axis3d.py b/lib/mpl_toolkits/mplot3d/axis3d.py
@@ -135,9 +135,7 @@ def init3d(self):
 
     def get_tick_positions(self):
         majorLocs = self.major.locator()
-        self.major.formatter.set_locs(majorLocs)
-        majorLabels = [self.major.formatter(val, i)
-                       for i, val in enumerate(majorLocs)]
+        majorLabels = self.major.formatter.format_ticks(majorLocs)
         return majorLabels, majorLocs
 
     def get_major_ticks(self, numticks=None):
@@ -236,11 +234,8 @@ def draw(self, renderer):
             locmin, locmax = locmax, locmin
 
         # Rudimentary clipping
-        majorLocs = [loc for loc in majorLocs if
-                     locmin <= loc <= locmax]
-        self.major.formatter.set_locs(majorLocs)
-        majorLabels = [self.major.formatter(val, i)
-                       for i, val in enumerate(majorLocs)]
+        majorLocs = [loc for loc in majorLocs if locmin <= loc <= locmax]
+        majorLabels = self.major.formatter.format_ticks(majorLocs)
 
         mins, maxs, centers, deltas, tc, highs = self._get_coord_info(renderer)