Add mpl_args and PlotGeometry stroke_width

src/metpy/plots/declarative.py

@@ -56,13 +56,14 @@ def lookup_map_feature(feature_name):
     return feat.with_scale(scaler)
 
 
-def plot_kwargs(data):
+def plot_kwargs(data, args):
     """Set the keyword arguments for MapPanel plotting."""
     if hasattr(data.metpy, 'cartopy_crs'):
         # Conditionally add cartopy transform if we are on a map.
         kwargs = {'transform': data.metpy.cartopy_crs}
     else:
         kwargs = {}
+    kwargs.update(args)
     return kwargs
 
 
@@ -103,6 +104,19 @@ def __dir__(self):
             dir(type(self))
         )
 
+    mpl_args = Dict(allow_none=True)
+    mpl_args.__doc__ = """Supply a dictionary of valid Matplotlib keyword arguments to modify
+    how the plot variable is drawn.
+
+    Using this attribute you must choose the appropriate keyword arguments (kwargs) based on
+    what you are plotting (e.g., contours, color-filled contours, image plot, etc.). This is
+    available for all plot types (ContourPlot, FilledContourPlot, RasterPlot, ImagePlot,
+    BarbPlot, ArrowPlot, PlotGeometry, and PlotObs). For PlotObs, the kwargs are those to
+    specify the StationPlot object. NOTE: Setting the mpl_args trait will override
+    any other trait that corresponds to a specific kwarg for the particular plot type
+    (e.g., linecolor, linewidth).
+    """
+
 
 class Panel(MetPyHasTraits):
     """Draw one or more plots."""
@@ -942,20 +956,17 @@ def _build(self):
         """Build the plot by calling any plotting methods as necessary."""
         x_like, y_like, imdata = self.plotdata
 
-        kwargs = plot_kwargs(imdata)
+        kwargs = plot_kwargs(imdata, self.mpl_args)
 
         # If we're on a map, we use min/max for y and manually figure out origin to try to
         # avoid upside down images created by images where y[0] > y[-1], as well as
         # specifying the transform
         kwargs['extent'] = (x_like[0], x_like[-1], y_like.min(), y_like.max())
         kwargs['origin'] = 'upper' if y_like[0] > y_like[-1] else 'lower'
+        kwargs.setdefault('cmap', self._cmap_obj)
+        kwargs.setdefault('norm', self._norm_obj)
 
-        self.handle = self.parent.ax.imshow(
-            imdata,
-            cmap=self._cmap_obj,
-            norm=self._norm_obj,
-            **kwargs
-        )
+        self.handle = self.parent.ax.imshow(imdata, **kwargs)
 
 
 @exporter.export
@@ -999,11 +1010,12 @@ def _build(self):
         """Build the plot by calling any plotting methods as necessary."""
         x_like, y_like, imdata = self.plotdata
 
-        kwargs = plot_kwargs(imdata)
+        kwargs = plot_kwargs(imdata, self.mpl_args)
+        kwargs.setdefault('linewidths', self.linewidth)
+        kwargs.setdefault('colors', self.linecolor)
+        kwargs.setdefault('linestyles', self.linestyle)
 
-        self.handle = self.parent.ax.contour(x_like, y_like, imdata, self.contours,
-                                             colors=self.linecolor, linewidths=self.linewidth,
-                                             linestyles=self.linestyle, **kwargs)
+        self.handle = self.parent.ax.contour(x_like, y_like, imdata, self.contours, **kwargs)
         if self.clabels:
             self.handle.clabel(inline=1, fmt='%.0f', inline_spacing=8,
                                use_clabeltext=True, fontsize=self.label_fontsize)
@@ -1024,11 +1036,11 @@ def _build(self):
         """Build the plot by calling any plotting methods as necessary."""
         x_like, y_like, imdata = self.plotdata
 
-        kwargs = plot_kwargs(imdata)
+        kwargs = plot_kwargs(imdata, self.mpl_args)
+        kwargs.setdefault('cmap', self._cmap_obj)
+        kwargs.setdefault('norm', self._norm_obj)
 
-        self.handle = self.parent.ax.contourf(x_like, y_like, imdata, self.contours,
-                                              cmap=self._cmap_obj, norm=self._norm_obj,
-                                              **kwargs)
+        self.handle = self.parent.ax.contourf(x_like, y_like, imdata, self.contours, **kwargs)
 
 
 @exporter.export
@@ -1046,11 +1058,11 @@ def _build(self):
         """Build the raster plot by calling any plotting methods as necessary."""
         x_like, y_like, imdata = self.plotdata
 
-        kwargs = plot_kwargs(imdata)
+        kwargs = plot_kwargs(imdata, self.mpl_args)
+        kwargs.setdefault('cmap', self._cmap_obj)
+        kwargs.setdefault('norm', self._norm_obj)
 
-        self.handle = self.parent.ax.pcolormesh(x_like, y_like, imdata,
-                                                cmap=self._cmap_obj, norm=self._norm_obj,
-                                                **kwargs)
+        self.handle = self.parent.ax.pcolormesh(x_like, y_like, imdata, **kwargs)
 
 
 @exporter.export
@@ -1225,7 +1237,11 @@ def _build(self):
         """Build the plot by calling needed plotting methods as necessary."""
         x_like, y_like, u, v = self.plotdata
 
-        kwargs = plot_kwargs(u)
+        kwargs = plot_kwargs(u, self.mpl_args)
+        kwargs.setdefault('color', self.color)
+        kwargs.setdefault('pivot', self.pivot)
+        kwargs.setdefault('length', self.barblength)
+        kwargs.setdefault('zorder', 2)
 
         # Conditionally apply the proper transform
         if 'transform' in kwargs and self.earth_relative:
@@ -1236,7 +1252,7 @@ def _build(self):
         self.handle = self.parent.ax.barbs(
             x_like[wind_slice], y_like[wind_slice],
             u.values[wind_slice], v.values[wind_slice],
-            color=self.color, pivot=self.pivot, length=self.barblength, zorder=2, **kwargs)
+            **kwargs)
 
 
 @exporter.export
@@ -1287,7 +1303,10 @@ def _build(self):
         """Build the plot by calling needed plotting methods as necessary."""
         x_like, y_like, u, v = self.plotdata
 
-        kwargs = plot_kwargs(u)
+        kwargs = plot_kwargs(u, self.mpl_args)
+        kwargs.setdefault('color', self.color)
+        kwargs.setdefault('pivot', self.pivot)
+        kwargs.setdefault('scale', self.arrowscale)
 
         # Conditionally apply the proper transform
         if 'transform' in kwargs and self.earth_relative:
@@ -1298,7 +1317,7 @@ def _build(self):
         self.handle = self.parent.ax.quiver(
             x_like[wind_slice], y_like[wind_slice],
             u.values[wind_slice], v.values[wind_slice],
-            color=self.color, pivot=self.pivot, scale=self.arrowscale, **kwargs)
+            **kwargs)
 
         # The order here needs to match the order of the tuple
         if self.arrowkey is not None:
@@ -1573,9 +1592,12 @@ def _build(self):
         scale = 1. if self.parent._proj_obj == ccrs.PlateCarree() else 100000.
         point_locs = self.parent._proj_obj.transform_points(ccrs.PlateCarree(), lon, lat)
         subset = reduce_point_density(point_locs, self.reduce_points * scale)
+        kwargs = self.mpl_args
+        kwargs.setdefault('clip_on', True)
+        kwargs.setdefault('transform', ccrs.PlateCarree())
+        kwargs.setdefault('fontsize', self.fontsize)
 
-        self.handle = StationPlot(self.parent.ax, lon[subset], lat[subset], clip_on=True,
-                                  transform=ccrs.PlateCarree(), fontsize=self.fontsize)
+        self.handle = StationPlot(self.parent.ax, lon[subset], lat[subset], **kwargs)
 
         for i, ob_type in enumerate(self.fields):
             field_kwargs = {}
@@ -1673,6 +1695,17 @@ class PlotGeometry(MetPyHasTraits):
     the sequence of colors as needed. Default value is black.
     """
 
+    stroke_width = Union([Instance(collections.abc.Iterable), Float()], default_value=[1],
+                         allow_none=True)
+    stroke_width.__doc__ = """Stroke width(s) for polygons and lines.
+
+    A single integer or floating point value or collection of values representing the size of
+    the stroke width. If a collection, the first value corresponds to the first Shapely
+    object in `geometry`, the second value corresponds to the second Shapely object, and so on.
+    If `stroke_width` is shorter than `geometry`, `stroke_width` cycles back to the beginning,
+    repeating the sequence of values as needed. Default value is 1.
+    """
+
     marker = Unicode(default_value='.', allow_none=False)
     marker.__doc__ = """Symbol used to denote points.
 
@@ -1851,27 +1884,38 @@ def _build(self):
                                 else self.label_edgecolor)
         self.label_facecolor = (['none'] if self.label_facecolor is None
                                 else self.label_facecolor)
+        kwargs = self.mpl_args
 
         # Each Shapely object is plotted separately with its corresponding colors and label
-        for geo_obj, stroke, fill, label, fontcolor, fontoutline in zip(
-                self.geometry, cycle(self.stroke), cycle(self.fill), cycle(self.labels),
-                cycle(self.label_facecolor), cycle(self.label_edgecolor)):
+        for geo_obj, stroke, strokewidth, fill, label, fontcolor, fontoutline in zip(
+                self.geometry, cycle(self.stroke), cycle(self.stroke_width), cycle(self.fill),
+                cycle(self.labels), cycle(self.label_facecolor), cycle(self.label_edgecolor)):
             # Plot the Shapely object with the appropriate method and colors
             if isinstance(geo_obj, (MultiPolygon, Polygon)):
-                self.parent.ax.add_geometries([geo_obj], edgecolor=stroke,
-                                              facecolor=fill, crs=ccrs.PlateCarree())
+                kwargs.setdefault('edgecolor', stroke)
+                kwargs.setdefault('linewidths', strokewidth)
+                kwargs.setdefault('facecolor', fill)
+                kwargs.setdefault('crs', ccrs.PlateCarree())
+                self.parent.ax.add_geometries([geo_obj], **kwargs)
             elif isinstance(geo_obj, (MultiLineString, LineString)):
-                self.parent.ax.add_geometries([geo_obj], edgecolor=stroke,
-                                              facecolor='none', crs=ccrs.PlateCarree())
+                kwargs.setdefault('edgecolor', stroke)
+                kwargs.setdefault('linewidths', strokewidth)
+                kwargs.setdefault('facecolor', 'none')
+                kwargs.setdefault('crs', ccrs.PlateCarree())
+                self.parent.ax.add_geometries([geo_obj], **kwargs)
             elif isinstance(geo_obj, MultiPoint):
+                kwargs.setdefault('color', fill)
+                kwargs.setdefault('marker', self.marker)
+                kwargs.setdefault('transform', ccrs.PlateCarree())
                 for point in geo_obj.geoms:
                     lon, lat = point.coords[0]
-                    self.parent.ax.plot(lon, lat, color=fill, marker=self.marker,
-                                        transform=ccrs.PlateCarree())
+                    self.parent.ax.plot(lon, lat, **kwargs)
             elif isinstance(geo_obj, Point):
+                kwargs.setdefault('color', fill)
+                kwargs.setdefault('marker', self.marker)
+                kwargs.setdefault('transform', ccrs.PlateCarree())
                 lon, lat = geo_obj.coords[0]
-                self.parent.ax.plot(lon, lat, color=fill, marker=self.marker,
-                                    transform=ccrs.PlateCarree())
+                self.parent.ax.plot(lon, lat, **kwargs)
 
             # Plot labels if provided
             if label: