added dashed red diagonal on scatterplot (#63)

* added dashed red diagonal and use of empty dots in scatterplot

* formatting fixed

Co-authored-by: Massimiliano Lupo Pasini <7ml@ornl.gov>

hydragnn/postprocess/visualizer.py

@@ -113,7 +113,8 @@ def __scatter_impl(
         y_label=None,
         xylim_equal=False,
     ):
-        ax.scatter(x, y, s, c, marker)
+        ax.scatter(x, y, s=s, edgecolor="b", marker=marker, facecolor="none")
+
         ax.set_title(title)
         ax.set_xlabel(x_label)
         ax.set_ylabel(y_label)
@@ -124,6 +125,8 @@ def __scatter_impl(
             ax.set_xlim(minimum, maximum)
             ax.set_ylim(minimum, maximum)
 
+        self.add_identity(ax, color="r", ls="--")
+
     def create_plot_global_analysis(
         self, varname, true_values, predicted_values, save_plot=True
     ):
@@ -550,6 +553,21 @@ def create_scatter_plot_nodes_vec(
                 fig.savefig(f"./logs/{self.model_with_config_name}/" + varname + ".png")
             plt.close()
 
+    def add_identity(self, axes, *line_args, **line_kwargs):
+        (identity,) = axes.plot([], [], *line_args, **line_kwargs)
+
+        def callback(axes):
+            low_x, high_x = axes.get_xlim()
+            low_y, high_y = axes.get_ylim()
+            low = max(low_x, low_y)
+            high = min(high_x, high_y)
+            identity.set_data([low, high], [low, high])
+
+        callback(axes)
+        axes.callbacks.connect("xlim_changed", callback)
+        axes.callbacks.connect("ylim_changed", callback)
+        return axes
+
     def plot_history(
         self,
         total_loss_train,