Added rate_limit to Streamz pane (#769)

* Added rate_limit to Streamz pane * Updates to docs
holoviz · Nov 12, 2019 · 35c8b50 · 35c8b50
1 parent bdc073c
commit 35c8b50
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Showing 2 changed files with 11 additions and 7 deletions.
diff --git a/examples/reference/panes/Streamz.ipynb b/examples/reference/panes/Streamz.ipynb
@@ -25,6 +25,7 @@
     "\n",
     "* **``always_watch``** (boolean, default=False): Whether to watch the stream even when not displayed.\n",
     "* **``object``** (streamz.Stream): The streamz.Stream object being watched\n",
+    "* **``rate_limit``** (floa, default=0.1): The minimum interval between events.\n",
     "\n",
     "___"
    ]
@@ -82,7 +83,7 @@
     "        y='y',\n",
     "    )\n",
     "\n",
-    "altair_stream = df.cumsum().stream.sliding_window(100).map(line_plot)\n",
+    "altair_stream = df.cumsum().stream.sliding_window(50).map(line_plot)\n",
     "\n",
     "altair_pane = pn.pane.Streamz(altair_stream, height=350, always_watch=True)\n",
     "\n",
@@ -105,10 +106,10 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import time\n",
-    "for i in range(100):\n",
-    "    time.sleep(0.2)\n",
-    "    df.emit(pd.DataFrame({'y': [np.random.randn()]}, index=pd.DatetimeIndex([pd.datetime.now()])))"
+    "def emit():\n",
+    "    df.emit(pd.DataFrame({'y': [np.random.randn()]}, index=pd.DatetimeIndex([pd.datetime.now()])))\n",
+    "\n",
+    "altair_pane.add_periodic_callback(emit, period=100)"
    ]
   }
  ],

diff --git a/panel/pane/streamz.py b/panel/pane/streamz.py
@@ -15,21 +15,24 @@ class Streamz(ReplacementPane):
     always_watch = param.Boolean(default=False, doc="""
         Whether to watch even when not displayed.""")
 
+    rate_limit = param.Number(default=0.1, bounds=(0, None), doc="""
+        The minimum interval between events.""")
+
     def __init__(self, object=None, **params):
         super(Streamz, self).__init__(object, **params)
         self._stream = None
         if self.always_watch:
             self._setup_stream()
 
-    @param.depends('object', 'always_watch', watch=True)
+    @param.depends('always_watch', 'object', 'rate_limit', watch=True)
     def _setup_stream(self):
         if self.object is None or (self.always_watch and self._stream):
             return
         elif self._stream:
             self._stream.destroy()
             self._stream = None
         if self._pane._models or self.always_watch:
-            self._stream = self.object.latest().rate_limit(0.5).gather()
+            self._stream = self.object.latest().rate_limit(self.rate_limit).gather()
             self._stream.sink(self._update_pane)
 
     def _get_model(self, doc, root=None, parent=None, comm=None):