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Datashader artist and colorbars regression #1069

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#1070
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Datashader artist and colorbars regression#1069
#1070
@maximlt

Description

@maximlt
maximlt
opened on Apr 14, 2022

Bug found in the interactivity page of the getting started guide, of the dev site.

To reproduce:

import pandas as pd
import numpy as np
import datashader as ds
import datashader.transfer_functions as tf
from collections import OrderedDict as odict
import matplotlib.pyplot as plt
from datashader.mpl_ext import dsshow, alpha_colormap
from mpl_toolkits.axes_grid1 import ImageGrid


num=100000
np.random.seed(1)

dists = {cat: pd.DataFrame(odict([('x',np.random.normal(x,s,num)), 
                                  ('y',np.random.normal(y,s,num)), 
                                  ('val',val), 
                                  ('cat',cat)]))      
         for x,  y,  s,  val, cat in 
         [(  2,  2, 0.03, 10, "d1"), 
          (  2, -2, 0.10, 20, "d2"), 
          ( -2, -2, 0.50, 30, "d3"), 
          ( -2,  2, 1.00, 40, "d4"), 
          (  0,  0, 3.00, 50, "d5")] }

df = pd.concat(dists,ignore_index=True)
df["cat"]=df["cat"].astype("category")

%matplotlib inline

fig = plt.figure(figsize=(9, 9))

# Here, we create a grid of axes using ImageGrid
# https://matplotlib.org/3.1.0/gallery/axes_grid1/demo_axes_grid.html 
grid = ImageGrid(fig, 111, nrows_ncols=(2, 2), axes_pad=0.5, share_all=True,
                 cbar_location="right", cbar_mode="each", cbar_size="5%", cbar_pad="2%")

artist0 = dsshow(df, ds.Point('x', 'y'), ds.count(), vmax=1000, aspect='equal', ax=grid[0])

plt.colorbar(artist0, cax=grid.cbar_axes[0]);
grid[0].set_title('Point density (linear scale, clipped)');

artist1 = dsshow(df, ds.Point('x', 'y'), ds.mean('val'), cmap='inferno', aspect='equal', ax=grid[1])
plt.colorbar(artist1, cax=grid.cbar_axes[1]);
grid[1].set_title('Mean point value (linear scale)');

dsblue=['lightblue', 'darkblue']
artist2 = dsshow(df, ds.Point('x', 'y'), ds.count(), norm='log', cmap=dsblue, aspect='equal', ax=grid[2])
plt.colorbar(artist2, cax=grid.cbar_axes[2]);
grid[2].set_title('Point density (log scale)');

artist3 = dsshow(df, ds.Point('x', 'y'), norm='log', cmap=alpha_colormap('#ffffff', 40, 255), ax=grid[3])
grid[3].set_facecolor('#000000');
grid.cbar_axes[3].set_visible(False);
grid[3].set_title('Point density (log, alpha-based colormap)');
Traceback 
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/IPython/core/formatters.py:339, in BaseFormatter.__call__(self, obj)
    337     pass
    338 else:
--> 339     return printer(obj)
    340 # Finally look for special method names
    341 method = get_real_method(obj, self.print_method)

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/IPython/core/pylabtools.py:151, in print_figure(fig, fmt, bbox_inches, base64, **kwargs)
    148     from matplotlib.backend_bases import FigureCanvasBase
    149     FigureCanvasBase(fig)
--> 151 fig.canvas.print_figure(bytes_io, **kw)
    152 data = bytes_io.getvalue()
    153 if fmt == 'svg':

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/backend_bases.py:2295, in FigureCanvasBase.print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, bbox_inches, pad_inches, bbox_extra_artists, backend, **kwargs)
   2289     renderer = _get_renderer(
   2290         self.figure,
   2291         functools.partial(
   2292             print_method, orientation=orientation)
   2293     )
   2294     with getattr(renderer, "_draw_disabled", nullcontext)():
-> 2295         self.figure.draw(renderer)
   2297 if bbox_inches:
   2298     if bbox_inches == "tight":

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/artist.py:73, in _finalize_rasterization.<locals>.draw_wrapper(artist, renderer, *args, **kwargs)
     71 @wraps(draw)
     72 def draw_wrapper(artist, renderer, *args, **kwargs):
---> 73     result = draw(artist, renderer, *args, **kwargs)
     74     if renderer._rasterizing:
     75         renderer.stop_rasterizing()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/artist.py:50, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     47     if artist.get_agg_filter() is not None:
     48         renderer.start_filter()
---> 50     return draw(artist, renderer)
     51 finally:
     52     if artist.get_agg_filter() is not None:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/figure.py:2810, in Figure.draw(self, renderer)
   2807         # ValueError can occur when resizing a window.
   2809 self.patch.draw(renderer)
-> 2810 mimage._draw_list_compositing_images(
   2811     renderer, self, artists, self.suppressComposite)
   2813 for sfig in self.subfigs:
   2814     sfig.draw(renderer)

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/image.py:132, in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
    130 if not_composite or not has_images:
    131     for a in artists:
--> 132         a.draw(renderer)
    133 else:
    134     # Composite any adjacent images together
    135     image_group = []

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/artist.py:50, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     47     if artist.get_agg_filter() is not None:
     48         renderer.start_filter()
---> 50     return draw(artist, renderer)
     51 finally:
     52     if artist.get_agg_filter() is not None:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/axes/_base.py:3082, in _AxesBase.draw(self, renderer)
   3079         a.draw(renderer)
   3080     renderer.stop_rasterizing()
-> 3082 mimage._draw_list_compositing_images(
   3083     renderer, self, artists, self.figure.suppressComposite)
   3085 renderer.close_group('axes')
   3086 self.stale = False

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/image.py:132, in _draw_list_compositing_images(renderer, parent, artists, suppress_composite)
    130 if not_composite or not has_images:
    131     for a in artists:
--> 132         a.draw(renderer)
    133 else:
    134     # Composite any adjacent images together
    135     image_group = []

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/artist.py:50, in allow_rasterization.<locals>.draw_wrapper(artist, renderer)
     47     if artist.get_agg_filter() is not None:
     48         renderer.start_filter()
---> 50     return draw(artist, renderer)
     51 finally:
     52     if artist.get_agg_filter() is not None:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/image.py:646, in _ImageBase.draw(self, renderer, *args, **kwargs)
    644         renderer.draw_image(gc, l, b, im, trans)
    645 else:
--> 646     im, l, b, trans = self.make_image(
    647         renderer, renderer.get_image_magnification())
    648     if im is not None:
    649         renderer.draw_image(gc, l, b, im)

File ~/work/dev/datashader/datashader/mpl_ext.py:288, in DSArtist.make_image(self, renderer, magnification, unsampled)
    285 print('3', self.norm, self.norm.vmin, self.norm.vmax)
    287 # Normalize and color to make an RGBA array
--> 288 rgba = self.shade(binned)
    289 if self.shade_hook is not None:
    290     img = to_ds_image(binned, rgba)

File ~/work/dev/datashader/datashader/mpl_ext.py:412, in ScalarDSArtist.shade(self, binned)
    410 print('_vmin,_vmax', self._vmin, self._vmax)
    411 # if self._vmin is not None:
--> 412 self.norm.vmin = self._vmin
    413 # if self._vmax is not None:
    414 self.norm.vmax = self._vmax

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colors.py:1150, in Normalize.vmin(self, value)
   1148 if value != self._vmin:
   1149     self._vmin = value
-> 1150     self._changed()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colors.py:1178, in Normalize._changed(self)
   1173 def _changed(self):
   1174     """
   1175     Call this whenever the norm is changed to notify all the
   1176     callback listeners to the 'changed' signal.
   1177     """
-> 1178     self.callbacks.process('changed')

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:292, in CallbackRegistry.process(self, s, *args, **kwargs)
    290 except Exception as exc:
    291     if self.exception_handler is not None:
--> 292         self.exception_handler(exc)
    293     else:
    294         raise

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:96, in _exception_printer(exc)
     94 def _exception_printer(exc):
     95     if _get_running_interactive_framework() in ["headless", None]:
---> 96         raise exc
     97     else:
     98         traceback.print_exc()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:287, in CallbackRegistry.process(self, s, *args, **kwargs)
    285 if func is not None:
    286     try:
--> 287         func(*args, **kwargs)
    288     # this does not capture KeyboardInterrupt, SystemExit,
    289     # and GeneratorExit
    290     except Exception as exc:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/image.py:308, in _ImageBase.changed(self)
    306 self._imcache = None
    307 self._rgbacache = None
--> 308 cm.ScalarMappable.changed(self)

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cm.py:618, in ScalarMappable.changed(self)
    613 def changed(self):
    614     """
    615     Call this whenever the mappable is changed to notify all the
    616     callbackSM listeners to the 'changed' signal.
    617     """
--> 618     self.callbacks.process('changed', self)
    619     self.stale = True

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:292, in CallbackRegistry.process(self, s, *args, **kwargs)
    290 except Exception as exc:
    291     if self.exception_handler is not None:
--> 292         self.exception_handler(exc)
    293     else:
    294         raise

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:96, in _exception_printer(exc)
     94 def _exception_printer(exc):
     95     if _get_running_interactive_framework() in ["headless", None]:
---> 96         raise exc
     97     else:
     98         traceback.print_exc()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:287, in CallbackRegistry.process(self, s, *args, **kwargs)
    285 if func is not None:
    286     try:
--> 287         func(*args, **kwargs)
    288     # this does not capture KeyboardInterrupt, SystemExit,
    289     # and GeneratorExit
    290     except Exception as exc:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colorbar.py:547, in Colorbar.update_normal(self, mappable)
    544     self.norm = mappable.norm
    545     self._reset_locator_formatter_scale()
--> 547 self.draw_all()
    548 if isinstance(self.mappable, contour.ContourSet):
    549     CS = self.mappable

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colorbar.py:574, in Colorbar.draw_all(self)
    568 self._short_axis().set_ticks([], minor=True)
    570 # Set self._boundaries and self._values, including extensions.
    571 # self._boundaries are the edges of each square of color, and
    572 # self._values are the value to map into the norm to get the
    573 # color:
--> 574 self._process_values()
    575 # Set self.vmin and self.vmax to first and last boundary, excluding
    576 # extensions:
    577 self.vmin, self.vmax = self._boundaries[self._inside][[0, -1]]

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colorbar.py:1111, in Colorbar._process_values(self)
   1109 # transform from 0-1 to vmin-vmax:
   1110 if not self.norm.scaled():
-> 1111     self.norm.vmin = 0
   1112     self.norm.vmax = 1
   1113 self.norm.vmin, self.norm.vmax = mtransforms.nonsingular(
   1114     self.norm.vmin, self.norm.vmax, expander=0.1)

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colors.py:1150, in Normalize.vmin(self, value)
   1148 if value != self._vmin:
   1149     self._vmin = value
-> 1150     self._changed()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colors.py:1178, in Normalize._changed(self)
   1173 def _changed(self):
   1174     """
   1175     Call this whenever the norm is changed to notify all the
   1176     callback listeners to the 'changed' signal.
   1177     """
-> 1178     self.callbacks.process('changed')

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:292, in CallbackRegistry.process(self, s, *args, **kwargs)
    290 except Exception as exc:
    291     if self.exception_handler is not None:
--> 292         self.exception_handler(exc)
    293     else:
    294         raise

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:96, in _exception_printer(exc)
     94 def _exception_printer(exc):
     95     if _get_running_interactive_framework() in ["headless", None]:
---> 96         raise exc
     97     else:
     98         traceback.print_exc()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:287, in CallbackRegistry.process(self, s, *args, **kwargs)
    285 if func is not None:
    286     try:
--> 287         func(*args, **kwargs)
    288     # this does not capture KeyboardInterrupt, SystemExit,
    289     # and GeneratorExit
    290     except Exception as exc:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/image.py:308, in _ImageBase.changed(self)
    306 self._imcache = None
    307 self._rgbacache = None
--> 308 cm.ScalarMappable.changed(self)

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cm.py:618, in ScalarMappable.changed(self)
    613 def changed(self):
    614     """
    615     Call this whenever the mappable is changed to notify all the
    616     callbackSM listeners to the 'changed' signal.
    617     """
--> 618     self.callbacks.process('changed', self)
    619     self.stale = True

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:292, in CallbackRegistry.process(self, s, *args, **kwargs)
    290 except Exception as exc:
    291     if self.exception_handler is not None:
--> 292         self.exception_handler(exc)
    293     else:
    294         raise

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:96, in _exception_printer(exc)
     94 def _exception_printer(exc):
     95     if _get_running_interactive_framework() in ["headless", None]:
---> 96         raise exc
     97     else:
     98         traceback.print_exc()

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/cbook/__init__.py:287, in CallbackRegistry.process(self, s, *args, **kwargs)
    285 if func is not None:
    286     try:
--> 287         func(*args, **kwargs)
    288     # this does not capture KeyboardInterrupt, SystemExit,
    289     # and GeneratorExit
    290     except Exception as exc:

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colorbar.py:547, in Colorbar.update_normal(self, mappable)
    544     self.norm = mappable.norm
    545     self._reset_locator_formatter_scale()
--> 547 self.draw_all()
    548 if isinstance(self.mappable, contour.ContourSet):
    549     CS = self.mappable

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colorbar.py:574, in Colorbar.draw_all(self)
    568 self._short_axis().set_ticks([], minor=True)
    570 # Set self._boundaries and self._values, including extensions.
    571 # self._boundaries are the edges of each square of color, and
    572 # self._values are the value to map into the norm to get the
    573 # color:
--> 574 self._process_values()
    575 # Set self.vmin and self.vmax to first and last boundary, excluding
    576 # extensions:
    577 self.vmin, self.vmax = self._boundaries[self._inside][[0, -1]]

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colorbar.py:1117, in Colorbar._process_values(self)
   1113 self.norm.vmin, self.norm.vmax = mtransforms.nonsingular(
   1114     self.norm.vmin, self.norm.vmax, expander=0.1)
   1115 if (not isinstance(self.norm, colors.BoundaryNorm) and
   1116         (self.boundaries is None)):
-> 1117     b = self.norm.inverse(b)
   1119 self._boundaries = np.asarray(b, dtype=float)
   1120 self._values = 0.5 * (self._boundaries[:-1] + self._boundaries[1:])

File ~/miniconda3/envs/datashader-docs38/lib/python3.8/site-packages/matplotlib/colors.py:1554, in make_norm_from_scale.<locals>.Norm.inverse(self, value)
   1552 t_vmin, t_vmax = self._trf.transform([self.vmin, self.vmax])
   1553 if not np.isfinite([t_vmin, t_vmax]).all():
-> 1554     raise ValueError("Invalid vmin or vmax")
   1555 value, is_scalar = self.process_value(value)
   1556 rescaled = value * (t_vmax - t_vmin)

ValueError: Invalid vmin or vmax

<Figure size 648x648 with 8 Axes>

Commenting plt.colorbar(artist2, cax=grid.cbar_axes[2]); the code actually runs without eror, but the output images look different from the ones that are on the current site:

  • Currently on the 0.13.0 site:
    image

  • After running this code and commenting the line:
    image

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