DOCS plots for rank and crowding

docs/source/operators/plots.py

@@ -0,0 +1,54 @@
+import matplotlib.pyplot as plt
+
+
+def plot_pairs_3d(first, second, colors=("indigo", "firebrick"), **kwargs):
+
+    fig, ax = plt.subplots(1, 2, subplot_kw={'projection':'3d'}, **kwargs)
+
+    ax[0].scatter(
+        *first[1].T,
+        color=colors[0], label=first[0], marker="o",
+    )
+    ax[0].set_ylabel("$f_2$")
+    ax[0].set_xlabel("$f_1$")
+    ax[0].set_zlabel("$f_3$")
+    ax[0].legend()
+
+    ax[1].scatter(
+        *second[1].T,
+        color=colors[1], label=second[0], marker="o",
+    )
+    ax[1].set_ylabel("$f_2$")
+    ax[1].set_xlabel("$f_1$")
+    ax[1].set_zlabel("$f_3$")
+    ax[1].legend()
+
+    ax[0].view_init(elev=30, azim=30)
+    ax[1].view_init(elev=30, azim=30)
+
+    fig.tight_layout()
+    plt.show()
+
+
+def plot_pairs_2d(first, second, colors=("indigo", "firebrick"), **kwargs):
+
+    fig, ax = plt.subplots(1, 2, **kwargs)
+
+    ax[0].scatter(
+        *first[1].T,
+        color=colors[0], label=first[0], marker="o",
+    )
+    ax[0].set_ylabel("$f_2$")
+    ax[0].set_xlabel("$f_1$")
+    ax[0].legend()
+
+    ax[1].scatter(
+        *second[1].T,
+        color=colors[1], label=second[0], marker="o",
+    )
+    ax[1].set_ylabel("$f_2$")
+    ax[1].set_xlabel("$f_1$")
+    ax[1].legend()
+
+    fig.tight_layout()
+    plt.show()