Merge pull request #147 from QuLogic/simplify-colormap

Simplify colormap plotting

Makefile

@@ -50,8 +50,8 @@ check:
  ./check-num-pages.sh handout-tips.pdf 1
  ./check-num-pages.sh handout-beginner.pdf 1
  ./check-num-pages.sh handout-intermediate.pdf 1
- ./check-links.py cheatsheets.pdf
  ./check-diffs.py
+ ./check-links.py cheatsheets.pdf
 
 .PHONY: docs
 docs:

check-links.py

@@ -8,12 +8,12 @@
 
 refs = [ref for ref in pdf.get_references() if ref.reftype == 'url']
 
-status_codes = list(map(lambda ref: pdfx.downloader.get_status_code(ref.ref), refs))
+status_codes = [pdfx.downloader.get_status_code(ref.ref) for ref in refs]
 
-broken_links = [refs[idx].ref for idx in range(len(refs)) if status_codes[idx] != 200]
+broken_links = [(ref.ref, code) for ref, code in zip(refs, status_codes) if code != 200]
 
 # it seems that Twitter does not respond well to the link checker and throws a 400
-if all(['twitter.com' in url for url in broken_links]):
+if all(['twitter.com' in url for url, _ in broken_links]):
  sys.exit(0)
 else:
  print('Broken links:', broken_links)

scripts/colormaps.py

@@ -35,36 +35,14 @@
  'terrain', 'ocean', 'gist_earth', 'cubehelix', 'rainbow'
  )
 
-for cmap in cmaps:
- n = 512
+for name in cmaps:
+ # The maximum number of segments in a cmap is 256, and for anything smaller,
+ # the cmap will map as a suitably discrete set of colours.
+ Z = np.linspace(0, 1, 256).reshape(1, 256)
 
- if cmap in ['tab10']: n = 10
- if cmap in ['tab20', 'tab20b', 'tab20c']: n = 20
- if cmap in ['Pastel1', 'Set1']: n = 9
- if cmap in ['Pastel2', 'Accent', 'Dark2', 'Set2']: n = 8
- if cmap in ['Set3']: n = 12
- if cmap in ['Greys']: n = 11
- Z = np.linspace(0, 1, n).reshape(1, n)
-
- ax.imshow(Z, extent=[xmin, xmax, ymin, ymax], cmap=plt.get_cmap(cmap))
+ ax.imshow(Z, extent=[xmin, xmax, ymin, ymax], cmap=name)
  ax.set_xlim(xmin, xmax), ax.set_xticks([])
  ax.set_ylim(ymin, ymax), ax.set_yticks([])
 
- """
- if cmap == "tab10":
- x = np.linspace(xmin, xmax, 11, endpoint=True) + 0.5*(xmax-xmin)/11
- for i in range(10):
- ax.text(x[i], (ymin+ymax)/2, "C%d"%i, color="white", zorder=10,
- family = "Source Pro Serif", size=10, ha="center", va="center")
-
- if cmap == "Greys":
- x = np.linspace(xmin, xmax, 12, endpoint=True) + 0.5*(xmax-xmin)/12
- for i in range(11):
- color = "%.1f"%(i/10)
- text = "%.1f"%(1-i/10)
- ax.text(x[i], (ymin+ymax)/2, text, color=color, zorder=10,
- family = "Source Pro Serif", size=10, ha="center", va="center")
- """
-
- fig.savefig(ROOT_DIR / f"figures/colormap-{cmap}.pdf")
+ fig.savefig(ROOT_DIR / f"figures/colormap-{name}.pdf")
  ax.clear()

scripts/colors.py

@@ -33,12 +33,19 @@
 for name, colors in palettes.items():
  C = mpl.colors.to_rgba_array(colors).reshape((1, len(colors), 4))
  ax.imshow(C, extent=[xmin, xmax, ymin, ymax])
+
+ # Drop alpha by assuming we're on a white background PDF.
+ alpha = C[0, :, 3]
+ rgb = C[0, :, :3] * alpha[:, np.newaxis] + (1 - alpha[:, np.newaxis])
+ # Same calculation for luminance as
+ # https://matplotlib.org/stable/users/explain/colors/colors.html#comparison-between-x11-css4-and-xkcd-colors
+ luma = 0.299 * rgb[:, 0] + 0.587 * rgb[:, 1] + 0.114 * rgb[:, 2]
+
  dx = (xmax-xmin)/len(colors)
  for i in range(len(colors)):
- color = "white"
- if colors[i] in ['1.0', 'w']: color = "black"
+ text_color = "black" if luma[i] > 0.5 else "white"
  text = str(colors[i]).replace(' ', '')
- ax.text((i+0.5)*dx, (ymin+ymax)/2, text, color=color, zorder=10,
+ ax.text((i+0.5)*dx, (ymin+ymax)/2, text, color=text_color, zorder=10,
  family="Source Code Pro", size=9, ha="center", va="center")
 
  fig.savefig(ROOT_DIR / f"figures/colors-{name}.pdf")