First go at using a free port instead of defaulting to 8050

README.md

@@ -27,7 +27,9 @@ directly on a D-Wave quantum computer's quantum processing unit (QPU).
 
 ## Usage
 
-Run `python app.py` and open http://127.0.0.1:8050/ in your browser.  A
+Run `python app.py`. 
+A URL of the form http://127.0.0.1:***** will be printed in the console. 
+Open in the url in your browser.
 dropdown menu is provided to choose the dataset.
 
 To visualize feature redundancy, first activate the "Show redundancy" check box.

app.py

@@ -16,6 +16,7 @@
 # visit http://127.0.0.1:8050/ in your web browser.
 
 import json
+import socket
 
 from dash import Dash, html, dcc, Input, Output, State
 from dash.exceptions import PreventUpdate
@@ -307,6 +308,13 @@ def update_score_figure(feature_score_data, data_key):
     return children
 
 
+def find_free_port():
+    with socket.socket() as s:
+        s.bind(('', 0))            # Bind to a free port provided by the host.
+        return s.getsockname()[1]  # Return the port number assigned.
+
+
 if __name__ == '__main__':
     # Set dev_tools_ui=False or debug=False to disable the dev tools UI
-    app.run_server(debug=True, dev_tools_ui=False)
+    port = find_free_port()
+    app.run_server(debug=True, dev_tools_ui=False, port=port)