Merge f59177b into 5c660fa

docs/installing-oggm.rst

@@ -73,6 +73,8 @@ Optional:
     - progressbar2 (displays the download progress)
     - bottleneck (speeds up xarray operations)
     - dask (works nicely with xarray)
+    - `python-colorspace <https://github.com/retostauffer/python-colorspace>`_
+      (applies HCL-based color palettes to some graphics)
 
 
 .. _conda-install:
@@ -328,9 +330,10 @@ Now install further dependencies::
 
     $ pip install pyproj rasterio Pillow geopandas netcdf4 scikit-image configobj joblib xarray boto3 progressbar2 pytest motionless dask bottleneck
 
-Finally, install the salem library::
+Finally, install the salem and python-colorspace libraries::
 
     $ pip install git+https://github.com/fmaussion/salem.git
+    $ pip install git+https://github.com/retostauffer/python-colorspace.git
 
 OGGM and tests
 ~~~~~~~~~~~~~~

docs/whats-new.rst

@@ -13,6 +13,8 @@ New contributors to the project:
   cross-validation tools and an associated website.
 - **Philipp Gregor** (Master student, University of Innsbruck), added options
   to switch on lateral bed stress in the flowline ice dynamics
+- **Sadie Bartholomew** (Software Engineer, UK Met Office), added ability to
+  replace colormaps in graphics with HCL-based colors using python-colorspace.
 
 Breaking changes
 ~~~~~~~~~~~~~~~~
@@ -151,6 +153,9 @@ Enhancements
 - New ``process_dummy_cru_file`` taks to run OGGM with randomized CRU data
   (:pull:`603`).
   By `Fabien Maussion <https://github.com/fmaussion>`_.
+- Colormaps in some graphics are replaced with Hue-Chroma-Luminance (HCL) based
+  improvements when python-colorspace is (optionally) installed (:pull:`587`).
+  By `Sadie Bartholomew <https://github.com/sadielbartholomew>`_.
 
 
 Bug fixes

oggm/graphics.py

@@ -13,12 +13,30 @@
 import shapely.geometry as shpg
 from matplotlib import cm as colormap
 
+try:
+    # optional python-colorspace dependency for better (HCL-based) colormaps
+    from colorspace import sequential_hcl
+    USE_HCL_CMAP = True
+except ImportError:
+    USE_HCL_CMAP = False
+
 from oggm.core.flowline import FileModel
 from oggm import cfg, utils
 
 # Module logger
 log = logging.getLogger(__name__)
 
+# Set global colormaps
+ALTITUDE_CMAP = colormap.terrain
+if USE_HCL_CMAP:
+    CMAP_DIVS = 100  # number of discrete colours from continuous colormaps
+    THICKNESS_CMAP = sequential_hcl("Blue-Yellow", rev=True).cmap(CMAP_DIVS)
+    SECTION_THICKNESS_CMAP = THICKNESS_CMAP
+    GLACIER_THICKNESS_CMAP = THICKNESS_CMAP
+else:
+    SECTION_THICKNESS_CMAP = plt.cm.get_cmap('YlOrRd')
+    GLACIER_THICKNESS_CMAP = plt.get_cmap('viridis')
+
 
 def truncate_colormap(cmap, minval=0.0, maxval=1.0, n=256):
     """Remove extreme colors from a colormap."""
@@ -216,7 +234,7 @@ def plot_domain(gdirs, ax=None, smap=None):
     except ValueError:
         pass
 
-    cm = truncate_colormap(colormap.terrain, minval=0.25, maxval=1.0, n=256)
+    cm = truncate_colormap(ALTITUDE_CMAP, minval=0.25, maxval=1.0, n=256)
     smap.set_cmap(cm)
     smap.set_plot_params(nlevels=256)
 
@@ -256,7 +274,7 @@ def plot_centerlines(gdirs, ax=None, smap=None, use_flowlines=False,
     with utils.ncDataset(gdir.get_filepath('gridded_data')) as nc:
         topo = nc.variables['topo'][:]
 
-    cm = truncate_colormap(colormap.terrain, minval=0.25, maxval=1.0, n=256)
+    cm = truncate_colormap(ALTITUDE_CMAP, minval=0.25, maxval=1.0, n=256)
     smap.set_cmap(cm)
     smap.set_plot_params(nlevels=256)
     smap.set_data(topo)
@@ -464,9 +482,8 @@ def plot_inversion(gdirs, ax=None, smap=None, linewidth=3, vmax=None):
                 toplot_crs.append(crs)
             vol.extend(c['volume'])
 
-    cm = plt.cm.get_cmap('YlOrRd')
-    dl = salem.DataLevels(cmap=cm, nlevels=256, data=toplot_th,
-                          vmin=0, vmax=vmax)
+    dl = salem.DataLevels(cmap=SECTION_THICKNESS_CMAP, nlevels=256,
+                          data=toplot_th, vmin=0, vmax=vmax)
     colors = dl.to_rgb()
     for l, c, crs in zip(toplot_lines, colors, toplot_crs):
         smap.set_geometry(l, crs=crs, color=c,
@@ -516,7 +533,7 @@ def plot_distributed_thickness(gdirs, ax=None, smap=None, varname_suffix=''):
     for l in poly_pix.interiors:
         smap.set_geometry(l, crs=crs, color='black', linewidth=0.5)
 
-    smap.set_cmap(plt.get_cmap('viridis'))
+    smap.set_cmap(GLACIER_THICKNESS_CMAP)
     smap.set_plot_params(nlevels=256)
     smap.set_data(thick)
 
@@ -577,9 +594,8 @@ def plot_modeloutput_map(gdirs, ax=None, smap=None, model=None,
                 toplot_lines.append(line)
                 toplot_crs.append(crs)
 
-    cm = plt.cm.get_cmap('YlOrRd')
-    dl = salem.DataLevels(cmap=cm, nlevels=256, data=toplot_th,
-                          vmin=0, vmax=vmax)
+    dl = salem.DataLevels(cmap=SECTION_THICKNESS_CMAP, nlevels=256,
+                          data=toplot_th, vmin=0, vmax=vmax)
     colors = dl.to_rgb()
     for l, c, crs in zip(toplot_lines, colors, toplot_crs):
         smap.set_geometry(l, crs=crs, color=c,