Add push function to live plots

CHANGELOG.md

@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Added
 
 - LivePlot: Add `legend` shorthand function
+- LivePlot: Add `push` function
 - LivePlot: Add `reset` function
 - Sketch: Add a `reset` function
 

matplotlive/live_plot.py

@@ -107,16 +107,14 @@ def add_right(self, name: str, *args, **kwargs) -> None:
         self.__add(name, "right", *args, **kwargs)
 
     def send(self, name: str, value: float) -> None:
-        """Send a new value for a given time series.
+        """Send a new value to a time series, adding it if needed.
 
         Args:
             name: Name of the time series.
             value: New value for the series.
-            args: If adding, positional arguments for ``pyplot.plot``.
-            kwargs: If adding, keyword arguments for ``pyplot.plot``.
         """
         if name not in self.series:
-            self.add_left(name)  # used in readme example
+            self.add_left(name)
         # Deleting and appending is slightly faster than rolling an array of
         # size 20 (mean ± std. dev. of 7 runs, 100,000 loops each):
         #
@@ -132,6 +130,24 @@ def send(self, name: str, value: float) -> None:
         self.__nb_updates[name] += 1
         self.__max_updates = max(self.__max_updates, self.__nb_updates[name])
 
+    def push(self, name: str, value: float) -> None:
+        """Send a new value to an existing time series.
+
+        Args:
+            name: Name of the time series.
+            value: New value for the series.
+
+        Note:
+            The difference between :func:`send` and :func:`push` happens when
+            the series was not added: :func:`send` will create it, while
+            :func:`push` will skip. Pushing is convenient when monitoring many
+            signals: you can push all of them in your program, and maintain a
+            separate list of those to plot when adding them.
+        """
+        if name not in self.series:
+            return
+        return self.send(name, value)
+
     def update(self) -> None:
         """Update plot with latest time-series values.
 

tests/test_live_plot.py

@@ -57,13 +57,21 @@ def test_add_twice(self):
     def test_send(self):
         plot = self.make_test_plot()
         plot.send("foo", 1.0)
-        self.assertFalse("foo" in plot.series)
-        plot.add_left("foo")
         self.assertTrue("foo" in plot.series)
         plot.send("foo", 2.0)
         plot.send("foo", 3.0)
         self.assertAlmostEqual(plot.series["foo"][-1], 3.0)
 
+    def test_push(self):
+        plot = self.make_test_plot()
+        plot.push("foo", 1.0)
+        self.assertFalse("foo" in plot.series)
+        plot.add_left("foo")
+        self.assertTrue("foo" in plot.series)
+        plot.push("foo", 2.0)
+        plot.push("foo", 3.0)
+        self.assertAlmostEqual(plot.series["foo"][-1], 3.0)
+
     def test_update(self):
         plot = self.make_test_plot()
         plot.add_left("foo")