Merge pull request #447 from NCAR/coneff_11

Coneff 11

Gallery/Contours/NCL_coneff_11.py

@@ -0,0 +1,125 @@
+"""
+NCL_coneff_11.py
+================
+
+This script illustrates the following concepts:
+   - Filling contours with multiple styles of hatches
+   - Changing the color of hatches in a contour plot and colorbar
+   - Changing the size of hatches in a contour plot
+   - Changing the density hatches in a contour plot
+
+See following URLs to see the reproduced NCL plot & script:
+    - Original NCL script: https://www.ncl.ucar.edu/Applications/Scripts/coneff_11.ncl
+    - Original NCL plots: https://www.ncl.ucar.edu/Applications/Images/coneff_11_1_lg.png
+                          https://www.ncl.ucar.edu/Applications/Images/coneff_11_2_lg.png
+"""
+
+###############################################################################
+# Import packages:
+
+import numpy as np
+import xarray as xr
+import matplotlib.pyplot as plt
+
+import geocat.datafiles as gdf
+import geocat.viz as gv
+
+###############################################################################
+# Read in data
+
+# Open a netCDF data file using xarray default engine and load the data into xarrays
+ds = xr.open_dataset(gdf.get('netcdf_files/atmos.nc'), decode_times=False)
+
+# Select meridional wind at lowest pressure level
+v = ds.V.isel(time=0, lev=0)
+
+###############################################################################
+# Plot
+
+# Generate figure (set its size (width, height) in inches)
+plt.figure(figsize=(8, 10))
+ax = plt.axes()
+
+# Choose hatches to fill the contours
+hatches = ['/////', '/////', '/////', '/////', None, '..', '.', '.', '.']
+
+# Choose colors for the hatches
+colors = [
+    'coral', 'palegreen', 'royalblue', 'lemonchiffon', 'white', 'fuchsia',
+    'brown', 'cyan', 'mediumblue'
+]
+
+# Create a filled contour plot
+p = v.plot.contourf(ax=ax,
+                    vmin=-45.0,
+                    vmax=45,
+                    levels=10,
+                    add_colorbar=False,
+                    hatches=hatches,
+                    cmap='white')  # Use white cmap to have a white background
+
+# Set the colors for the hatches
+for i, collection in enumerate(p.collections):
+    collection.set_edgecolor(colors[i % len(colors)])
+    collection.set_linewidth(0.)
+
+# Set linewidth of hatches
+plt.rcParams['hatch.linewidth'] = 2.5
+
+# Plot the contour lines
+c = v.plot.contour(ax=ax,
+                   vmin=-45.0,
+                   vmax=45,
+                   levels=10,
+                   colors='k',
+                   linewidths=1,
+                   add_colorbar=False,
+                   linestyles='solid')
+
+# Add horizontal colorbar
+cbar = plt.colorbar(p,
+                    orientation='horizontal',
+                    shrink=0.97,
+                    aspect=10,
+                    pad=0.09,
+                    drawedges=True)
+cbar.ax.tick_params(labelsize=16)
+cbar.set_ticks(np.arange(-35, 40, 10))
+
+# Color the hatches in colorbar
+# We need to do this manually because matplotlib only uses information
+# from the contourf call to create the colorbar.
+for i, patch in enumerate(cbar.solids_patches):
+    patch.set(edgecolor=colors[i % len(colors)])
+
+# Use geocat-viz utility function to format latitude and longitude labels
+gv.add_lat_lon_ticklabels(ax)
+
+# Use geocat-viz utility function to format major and minor ticks
+gv.add_major_minor_ticks(ax,
+                         x_minor_per_major=2,
+                         y_minor_per_major=3,
+                         labelsize=16)
+
+# Use geocat-viz utility function to set titles and labels
+gv.set_titles_and_labels(ax,
+                         maintitle="Patterned Contour Plot",
+                         maintitlefontsize=18,
+                         lefttitle="meridional wind component",
+                         lefttitlefontsize=16,
+                         righttitle="m/s",
+                         righttitlefontsize=16)
+
+# Remove default x and y labels
+ax.set_xlabel(None)
+ax.set_ylabel(None)
+
+# Use geocat-viz utility function to set tick marks and tick labels
+gv.set_axes_limits_and_ticks(
+    ax,
+    xticks=np.arange(0, 360, 60),
+    yticks=np.arange(-60, 90, 30),
+    xticklabels=['0', '60E', '120E', '180', '120W', '60W'],
+    yticklabels=['60S', '30S', '0', '30N', '60N'])
+
+plt.show()