From 0377a46928fa1e0b2122e7f3576e43f7310d3a0c Mon Sep 17 00:00:00 2001
From: Will Robertson <wspr81@gmail.com>
Date: Wed, 20 Mar 2024 21:23:07 +1030
Subject: [PATCH] add flow_edge=True option

---
 ausankey/ausankey.py | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/ausankey/ausankey.py b/ausankey/ausankey.py
index c4b390f..6ea1472 100644
--- a/ausankey/ausankey.py
+++ b/ausankey/ausankey.py
@@ -35,6 +35,7 @@ def sankey(
     bar_gap=0.05,
     color_dict=None,
     colormap="viridis",
+    flow_edge=True,
     fontsize=14,
     frame_side="none",
     frame_gap=0.1,
@@ -84,6 +85,10 @@ def sankey(
     fontsize : int
         Font size of labels
 
+    flow_edge : bool
+        Whether to draw an edge to the flows.
+        Doesn't always look great when there is lots of branching and overlap.
+
     frame_side : str
         Whether to place a frame (horizontal rule) above or below the plot.
         Allowed values: `"none"`, `"top"`, `"bottom"`, or `"both"`
@@ -252,6 +257,7 @@ def sankey(
             label_order=label_order,
             color_dict=color_dict_new,
             fontsize=fontsize,
+            flow_edge=flow_edge,
             frame_gap=frame_gap,
             label_dict=label_dict or {},
             label_width=label_width,
@@ -279,6 +285,7 @@ def _sankey(
     data,
     color_dict=None,
     label_order=None,
+    flow_edge=None,
     fontsize=None,
     frame_gap=None,
     titles=None,
@@ -302,6 +309,14 @@ def _sankey(
     Some special-casing is used for plotting/labelling differently
     for the first and last cases.
     """
+    
+    if flow_edge:
+        edge_alpha = 1
+        edge_lw = 1
+    else:
+        edge_alpha = alpha
+        edge_lw = 0
+    
     labelind = 2 * ii
     weightind = 2 * ii + 1
 
@@ -328,7 +343,7 @@ def _sankey(
             pd.Series(data[weightind + 2]),
         ]
 
-    notnull = labels_lr[0].notnull() & labels_lr[1].notnull()
+    notnull = labels_lr[0].notnull() & labels_lr[1].notnull() & labels_lr[2].notnull()
     labels_lr[0] = labels_lr[0][notnull]
     labels_lr[1] = labels_lr[1][notnull]
     weights_lr[0] = weights_lr[0][notnull]
@@ -399,7 +414,7 @@ def draw_bar(x, dx, y, dy, label):
             y + dy,
             color=color_dict[label],
             alpha=1,
-            lw=0,
+            lw=edge_lw,
             snap=True,
         )
 
@@ -496,7 +511,7 @@ def draw_bar(x, dx, y, dy, label):
                     fontsize=fontsize,
                 )
 
-    # Plot strips
+    # Plot flows
     for lbl_l in bar_lr[0]:
         for lbl_r in bar_lr[1]:
             lind = labels_lr[0] == lbl_l
@@ -532,6 +547,22 @@ def draw_bar(x, dx, y, dy, label):
                     edgecolor="none",
                     snap=True,
                 )
+                ax.plot(
+                    xx[[jj, jj + 1]],
+                    ys_d[[jj, jj + 1]],
+                    color=cc[:, jj],
+                    alpha=edge_alpha,
+                    lw=edge_lw,
+                    snap=True,
+                )
+                ax.plot(
+                    xx[[jj, jj + 1]],
+                    ys_u[[jj, jj + 1]],
+                    color=cc[:, jj],
+                    alpha=edge_alpha,
+                    lw=edge_lw,
+                    snap=True,
+                )
 
 
 ###########################################