Merge pull request #410 from NCAR/native1_with_set_gridlines

add_lat_lon_gridlines in native_1 and native_2

Gallery/MapProjections/NCL_native_1.py

@@ -27,6 +27,53 @@
 import geocat.viz as gv
 import geocat.datafiles as gdf
 
+###############################################################################
+# Potential viz covenience function add_lat_lon_gridlines
+
+
+def add_lat_lon_gridlines(ax,
+                          projection=None,
+                          draw_labels=True,
+                          xlocator=np.arange(-180, 180, 15),
+                          ylocator=np.arange(-90, 90, 15),
+                          labelsize=12,
+                          **kwargs):
+    """Utility function that adds latitude and longtitude gridlines to the
+    plot.
+    Args:
+        ax (:class:`cartopy.mpl.geoaxes.GeoAxes`):
+            Current axes to the current figure.
+        projection (:class:`cartopy.crs.CRS`):
+            Defines a Cartopy Coordinate Reference System. If not given,
+            defaults to ccrs.PlateCarree()
+        draw_labels (:class:`bool`):
+            Toggle whether to draw labels, default to True.
+        xlocator, ylocator (:class:`numpy.ndarray` or list):
+            Arrays of fixed locations of the gridlines in the x and y coordinate of the given CRS.
+            Default to np.arange(-180, 180, 15) and np.arange(-90, 90, 15).
+        labelsize (:class:`float`):
+            Fontsizes of label fontsizes of x and y coordinates.
+        *kwargs* control line properties and are passed through to `matplotlib.collections.Collection`.
+    Return:
+        gl (:class:`cartopy.mpl.gridliner.Gridliner`):
+    """
+    import matplotlib.ticker as mticker
+
+    # Draw gridlines
+    gl = ax.gridlines(crs=projection,
+                      draw_labels=draw_labels,
+                      x_inline=False,
+                      y_inline=False,
+                      **kwargs)
+
+    gl.xlocator = mticker.FixedLocator(xlocator)
+    gl.ylocator = mticker.FixedLocator(ylocator)
+    gl.xlabel_style = {"rotation": 0, "size": labelsize}
+    gl.ylabel_style = {"rotation": 0, "size": labelsize}
+
+    return gl
+
+
 ###############################################################################
 # Read in data:
 nlat = 293
@@ -57,6 +104,15 @@
 # and 42.25N to 49.25N
 ax.set_extent([4.25, 15.25, 42.25, 49.25], ccrs.PlateCarree())
 
+# Draw gridlines
+add_lat_lon_gridlines(ax,
+                      xlocator=np.arange(4, 18, 2),
+                      ylocator=np.arange(43, 50),
+                      labelsize=14,
+                      linewidth=1,
+                      color='black',
+                      alpha=0.25)
+
 # Create colormap by choosing colors from existing colormap
 # The brightness of the colors in cmocean_speed increase linearly. This
 # makes the colormap easier to interpret for those with vision impairments

Gallery/MapProjections/NCL_native_2.py

@@ -37,6 +37,53 @@
                      decode_times=False)
 t = ds.FSD.isel(time=0)
 
+###############################################################################
+# Potential viz covenience function add_lat_lon_gridlines
+
+
+def add_lat_lon_gridlines(ax,
+                          projection=None,
+                          draw_labels=True,
+                          xlocator=np.arange(-180, 180, 15),
+                          ylocator=np.arange(-90, 90, 15),
+                          labelsize=12,
+                          **kwargs):
+    """Utility function that adds latitude and longtitude gridlines to the
+    plot.
+    Args:
+        ax (:class:`cartopy.mpl.geoaxes.GeoAxes`):
+            Current axes to the current figure.
+        projection (:class:`cartopy.crs.CRS`):
+            Defines a Cartopy Coordinate Reference System. If not given,
+            defaults to ccrs.PlateCarree()
+        draw_labels (:class:`bool`):
+            Toggle whether to draw labels, default to True.
+        xlocator, ylocator (:class:`numpy.ndarray` or list):
+            Arrays of fixed locations of the gridlines in the x and y coordinate of the given CRS.
+            Default to np.arange(-180, 180, 15) and np.arange(-90, 90, 15).
+        labelsize (:class:`float`):
+            Fontsizes of label fontsizes of x and y coordinates.
+        *kwargs* control line properties and are passed through to `matplotlib.collections.Collection`.
+    Return:
+        gl (:class:`cartopy.mpl.gridliner.Gridliner`):
+    """
+    import matplotlib.ticker as mticker
+
+    # Draw gridlines
+    gl = ax.gridlines(crs=projection,
+                      draw_labels=draw_labels,
+                      x_inline=False,
+                      y_inline=False,
+                      **kwargs)
+
+    gl.xlocator = mticker.FixedLocator(xlocator)
+    gl.ylocator = mticker.FixedLocator(ylocator)
+    gl.xlabel_style = {"rotation": 0, "size": labelsize}
+    gl.ylabel_style = {"rotation": 0, "size": labelsize}
+
+    return gl
+
+
 ###############################################################################
 # Plot:
 
@@ -68,12 +115,13 @@
                     ticks=cbar_ticks)
 
 # Draw gridlines
-gl = gv.add_lat_lon_gridlines(
-    ax,
-    color='grey',
-    labelsize=14,
-    xlocator=np.arange(130, 144, 4),  # longitudes for gridlines
-    ylocator=np.arange(36, 51, 2))  # latitudes for gridlines
+gl = add_lat_lon_gridlines(ax,
+                           xlocator=[130, 134, 138, 142],
+                           ylocator=[36, 38, 40, 42, 44, 46, 48, 50],
+                           labelsize=15,
+                           linewidth=1,
+                           color='black',
+                           alpha=0.25)
 
 # Remove lat/lon labels on top and right sides of plot
 gl.top_labels = False