Draft: cartopy projections

When specifying what projection to use when plotting, users currently have to provide as string identifying which cartopy projection they wish to use. These changes allow the user to instead provide a cartopy projection object. This allows them to fine tune the projection with key word arguments, something that is not currently easily done.

scripts/pyic_view.py

@@ -205,7 +205,8 @@ class view(object):
         res_menu.bind("<<ComboboxSelected>>", self.make_new_axis)
 
         # Button to activate zoom mode
-        self.zoom_button = ttk.Button(root, text="Enable Zoom", command=self.activate_zoom)
+        self.zoom_button = ttk.Button(root, text="Enable Zoom", 
+            command=self.activate_zoom)
         self.zoom_button.grid(row=3, column=2)
 
         # Variables to store zoom area
@@ -223,6 +224,12 @@ class view(object):
         res_menu.grid(row=3, column=3)
         res_menu.bind("<<ComboboxSelected>>", self.make_new_axis)
 
+        # checkbox for grid display
+        self.do_grid = tk.BooleanVar()
+        self.checkbox = tk.Checkbutton(root, text="Show grid", 
+            variable=self.do_grid, command=self.toggle_grid)
+        self.checkbox.grid(row=2, column=3)
+
         # initial plot
         self.plot_data()
         self.canvas.draw()
@@ -268,6 +275,7 @@ class view(object):
             # Ensure correct ordering of coordinates
             self.ax.set_xlim(min(x0, x1), max(x0, x1))
             self.ax.set_ylim(min(y0, y1), max(y0, y1))
+            #self.toggle_grid()
 
             # Remove the rectangle and redraw
             self.rect.remove()
@@ -330,6 +338,7 @@ class view(object):
             #self.X[valid], self.Y[valid], self.dai.data[valid], 
             self.X, self.Y, self.dai.data, 
             ax=self.ax, cax=self.cax)
+        # set ax limits
         if self.proj=="+proj=stere +lat_0=90 +lon_0=0":
             self.ax.set_xlim([-4660515.349812048,  4660515.349812048])
             self.ax.set_ylim([-4658959.2511977535, 4658959.2511977535])
@@ -339,6 +348,14 @@ class view(object):
         else:
             self.ax.set_xlim(self.X.min(), self.X.max())
             self.ax.set_ylim(self.Y.min(), self.Y.max())
+        # set ax labels
+        if self.proj=="None" or self.proj=="+proj=latlong":
+            #self.ax.set_xticks(np.arange(-180.,180.,45.))
+            #self.ax.set_yticks(np.arange(-90,90,45.))
+            pass
+        else:
+            self.ax.set_xticks([])
+            self.ax.set_yticks([])
         self.ax.set_facecolor('0.7')
         self.update_cmap()
         # set titles
@@ -475,6 +492,60 @@ class view(object):
           clim[1] = data.max().data
         return clim
 
+    def toggle_grid(self):
+        if self.do_grid.get():
+            print('Adding grid lines')
+            color='k'
+            linewidth=0.5
+            if self.proj=="+proj=stere +lat_0=90 +lon_0=0":
+                lon_c_vals = np.arange(-180.,180., 45.)
+                lat_c_vals = [40, 50, 60, 70, 80]
+            elif self.proj=="+proj=stere +lat_0=-90 +lon_0=0":
+                lon_c_vals = np.arange(-180.,180., 45.)
+                lat_c_vals = [-30, -40, -50, -60, -70, -80]
+            if self.proj=="None" or self.proj=="+proj=latlong":
+                lon_c_vals = self.ax.get_xticks()
+                lat_c_vals = self.ax.get_yticks()
+            else: 
+                lon_c_vals = np.arange(-180.,180., 45.)
+                lat_c_vals = np.arange(-90.,90., 45.)
+            #transformer = Proj.from_pipeline(self.proj)
+            nc = 51
+    
+            X_c = np.empty((1,nc))
+            Y_c = np.empty((1,nc))
+            for nn, lat_c_val in enumerate(lat_c_vals):
+              lon_c = np.linspace(-180,180,nc)
+              lat_c = lat_c_val*np.ones(nc)
+              if self.proj!="None":
+                  x_c, y_c = self.transformer.transform(
+                      lon_c, lat_c, direction='FORWARD')
+              else:
+                  x_c, y_c = lon_c, lat_c
+              X_c = np.concatenate([X_c, x_c[np.newaxis,:]], axis=0)
+              Y_c = np.concatenate([Y_c, y_c[np.newaxis,:]], axis=0)
+            for nn, lon_c_val in enumerate(lon_c_vals):
+              lon_c = lon_c_val*np.ones(nc)
+              lat_c = np.linspace(-90,90,nc)
+              if self.proj!="None":
+                  x_c, y_c = self.transformer.transform(
+                      lon_c, lat_c, direction='FORWARD')
+              else:
+                  x_c, y_c = lon_c, lat_c
+              X_c = np.concatenate([X_c, x_c[np.newaxis,:]], axis=0)
+              Y_c = np.concatenate([Y_c, y_c[np.newaxis,:]], axis=0)
+            self.hgs = []
+            for nn in range(X_c.shape[0]):
+                hg, = self.ax.plot(X_c[nn,:], Y_c[nn,:], 
+                    color=color, linewidth=linewidth)
+                self.hgs.append(hg)
+                #print(f'nn = {nn}, {self.hgs}')
+        else:
+            print('Removing grid lines')
+            for hg in self.hgs:
+                hg.remove()
+        self.canvas.draw()
+
     # capture mouse click, print coordinates and data
     def on_click(self, event):
         # Avoid clicking outside the axes