Add sankey node alignment

Author: LiamConnors

doc/python/sankey-diagram.md

@@ -6,7 +6,7 @@ jupyter:
       extension: .md
       format_name: markdown
       format_version: '1.3'
-      jupytext_version: 1.14.1
+      jupytext_version: 1.14.6
   kernel_info:
     name: python2
   kernelspec:
@@ -22,7 +22,7 @@ jupyter:
     name: python
     nbconvert_exporter: python
     pygments_lexer: ipython3
-    version: 3.8.8
+    version: 3.10.11
   plotly:
     description: How to make Sankey Diagrams in Python with Plotly.
     display_as: basic
@@ -49,7 +49,7 @@ fig = go.Figure(data=[go.Sankey(
       pad = 15,
       thickness = 20,
       line = dict(color = "black", width = 0.5),
-      label = ["A1", "A2", "B1", "B2", "C1", "C2"],
+#       label = ["A1", "A2", "A1", "B2", "C1", "C2"],
       color = "blue"
     ),
     link = dict(
@@ -229,7 +229,8 @@ fig = go.Figure(go.Sankey(
         label=['A', 'B', 'C', 'D', 'E', 'F'],
         x=[0.2, 0.1, 0.5, 0.7, 0.3, 0.5],
         y=[0.7, 0.5, 0.2, 0.4, 0.2, 0.3],
-        pad=10  
+        pad=10  ,
+        align="right",
     ),
     link=dict(
         arrowlen=15,
@@ -242,6 +243,53 @@ fig = go.Figure(go.Sankey(
 fig.show()
 ```
 
+### Node Alignment
+
+*New in 5.18*
+
+You can set the alignment of nodes using `node.align`. Here are two examples with the same `source` and `target`. The first example has nodes aligned "left" and the second has nodes aligned "right". `node.align` also supports "center" and "justify". "justify" is the default if `node.align` is not set, and is similar to aligning to the "left", except that nodes without outgoing links are moved to the right of the figure. 
+
+```python
+import plotly.graph_objects as go
+
+fig = go.Figure(go.Sankey(
+    arrangement='snap',
+    node=dict(
+        label=["0", "1", "2", "3", "4", "5"],
+        align='left'
+
+    ),
+    link=dict(
+        arrowlen=15,
+        source=[0, 1, 4, 2, 1],
+        target=[1, 4, 5, 4, 3],
+        value=[4, 2, 3, 1, 2]  
+    )
+))
+
+fig.show()
+```
+
+```python
+import plotly.graph_objects as go
+
+fig = go.Figure(go.Sankey(
+    arrangement='snap',
+    node=dict(
+        label=["0", "1", "2", "3", "4", "5"],
+        align="right",
+    ),
+    link=dict(
+        arrowlen=15,
+        source=[0, 1, 4, 2, 1],
+        target=[1, 4, 5, 4, 3],
+        value=[4, 2, 3, 1, 2]  
+    )
+))
+
+fig.show()
+```
+
 ### Reference
 
 See [https://plotly.com/python/reference/sankey](https://plotly.com/python/reference/sankey/) for more information and options!