Skip to content

Add _repr_png_ and _repr_html_ to Colormap objects. #17888

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
tacaswell merged 7 commits into from
Jul 12, 2020
Merged

Add _repr_png_ and _repr_html_ to Colormap objects. #17888

Show file tree
Hide file tree
Changes from 6 commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
1cfb18b
Created _repr_png_ and _repr_html_ for Colormap objects.
bdice Jul 11, 2020
d62cd55
Add a border to clarify the boundary of the image.
bdice Jul 11, 2020
d3ca7e2
Add tests for _repr_png_ and _repr_html_.
bdice Jul 11, 2020
34be66e
Added What's New entry.
bdice Jul 11, 2020
3da7fc4
Add PngInfo.
bdice Jul 11, 2020
a490278
Update PngInfo.
bdice Jul 11, 2020
9d46338
Enforce stricter tests for _repr_png_.
bdice Jul 12, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions doc/users/next_whats_new/colormap_repr.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
IPython representations for Colormap objects
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The `matplotlib.colors.Colormap` object now has image representations for
IPython / Jupyter backends. Cells returning a color map on the last line will
display an image of the color map.
32 changes: 32 additions & 0 deletions lib/matplotlib/colors.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -65,12 +65,17 @@
.. _xkcd color survey: https://xkcd.com/color/rgb/
"""

import base64
from collections.abc import Sized
import functools
import io
import itertools
from numbers import Number
import re
from PIL import Image
from PIL.PngImagePlugin import PngInfo

import matplotlib as mpl
import numpy as np
import matplotlib.cbook as cbook
from matplotlib import docstring
Expand Down Expand Up @@ -691,6 +696,33 @@ def reversed(self, name=None):
"""
raise NotImplementedError()

def _repr_png_(self):
"""Generate a PNG representation of the Colormap."""
IMAGE_SIZE = (400, 50)
X = np.tile(np.linspace(0, 1, IMAGE_SIZE[0]), (IMAGE_SIZE[1], 1))
pixels = self(X, bytes=True)
png_bytes = io.BytesIO()
title = self.name + ' color map'
author = f'Matplotlib v{mpl.__version__}, https://matplotlib.org'
pnginfo = PngInfo()
pnginfo.add_text('Title', title)
pnginfo.add_text('Description', title)
pnginfo.add_text('Author', author)
pnginfo.add_text('Software', author)
Image.fromarray(pixels).save(png_bytes, format='png', pnginfo=pnginfo)
return png_bytes.getvalue()

def _repr_html_(self):
"""Generate an HTML representation of the Colormap."""
png_bytes = self._repr_png_()
png_base64 = base64.b64encode(png_bytes).decode('ascii')
return ('<strong>' + self.name + '</strong>' +
'<img ' +
'alt="' + self.name + ' color map" ' +
'title="' + self.name + '"' +
'style="border: 1px solid #555;" ' +
'src="data:image/png;base64,' + png_base64 + '">')


class LinearSegmentedColormap(Colormap):
"""
Expand Down
13 changes: 13 additions & 0 deletions lib/matplotlib/tests/test_colors.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1135,3 +1135,16 @@ def test_hex_shorthand_notation():
def test_DivergingNorm_deprecated():
with pytest.warns(cbook.MatplotlibDeprecationWarning):
norm = mcolors.DivergingNorm(vcenter=0)


def test_repr_png():
cmap = plt.get_cmap('viridis')
png = cmap._repr_png_()
assert len(png) > 0


def test_repr_html():
cmap = plt.get_cmap('viridis')
html = cmap._repr_html_()
assert len(html) > 0
assert cmap.name in html