Return x and y separately

Simpler because that is what the plot command needs.

Trajectories/plot_traj.py

 #!/usr/bin/env python3
 
 import report_graph
-import numpy as np
 import random
 
 def get_extr_coord(traj, e_overestim, SHPC):
-    xy = []
+    x = []
+    y = []
 
     for node in traj:
         date_index, eddy_index = report_graph.node_to_date_eddy(node,
@@ -13,19 +13,19 @@ def get_extr_coord(traj, e_overestim, SHPC):
         i_slice = SHPC.get_slice(date_index)
         ishape = SHPC.comp_ishape(date_index, eddy_index, i_slice)
         shape = SHPC.get_reader(i_slice, layer = "extremum").shape(ishape)
-        xy.append(shape.points[0])
+        x.append(shape.points[0][0])
+        y.append(shape.points[0][1])
 
-    return np.array(xy)
+    return x, y
 
 def plot_single_traj(traj, e_overestim, SHPC, ax, src_crs, annotate_flag):
-    xy = get_extr_coord(traj, e_overestim, SHPC)
-    ax.plot(xy[:, 0], xy[:, 1], color = "red", transform = src_crs)
-    ax.plot(xy[0, 0], xy[0, 1], marker = "s", color = "black",
-            transform = src_crs)
+    x, y = get_extr_coord(traj, e_overestim, SHPC)
+    ax.plot(x, y, color = "red", transform = src_crs)
+    ax.plot(x[0], y[0], marker = "s", color = "black", transform = src_crs)
 
     if annotate_flag:
         ax.annotate(str(traj[0]),
-                    ax.projection.transform_point(xy[0, 0], xy[0, 1], src_crs),
+                    ax.projection.transform_point(x[0], y[0], src_crs),
                     xytext = (3 * random.random(), 3 * random.random()),
                     textcoords = "offset points")