Add a minimal plot 2d function

changes.d/703.feature

@@ -0,0 +1 @@
+New two dimensional plotting function ``qupulse.pulses.plotting.plot_2d``.

qupulse/pulses/plotting.py

@@ -6,13 +6,15 @@
     - plot: Plot a pulse using matplotlib.
 """
 
-from typing import Dict, Tuple, Any, Optional, Set, List, Union
+from typing import Dict, Tuple, Any, Optional, Set, List, Union, Mapping
 from numbers import Real
 
+import matplotlib.pyplot as plt
 import numpy as np
 import warnings
 import operator
 import itertools
+import functools
 
 from qupulse._program import waveforms
 from qupulse.utils.types import ChannelID, MeasurementWindow, has_type_interface
@@ -252,6 +254,56 @@ def plot(pulse: PulseTemplate,
     return axes.get_figure()
 
 
+@functools.singledispatch
+def plot_2d(program: Loop, channels: Tuple[ChannelID, ChannelID],
+            sample_rate: float = None,
+            ax: plt.Axes = None,
+            plot_kwargs: Mapping = None) -> plt.Figure:
+    """Plot the pulse/program in the plane of the given channels.
+
+    Args:
+        program: The program to plot
+        channels: (x_axis, y_axis) name tuple
+        sample_rate: Sample rate to use. Defaults to max(1000 samples per program, 10 per nano second)
+        ax: Axis to plot into.
+        plot_kwargs: Forwarded to the plot function.
+    """
+    if sample_rate is None:
+        sample_rate = max(1000 / program.duration, 10)
+
+    _, rendered, _ = render(program, sample_rate, plot_channels=set(channels))
+    x_y = np.array([rendered[channels[0]], rendered[channels[1]]])
+    keep = np.full(x_y.shape[1], fill_value=True)
+    keep[1:] = np.any(x_y[:, 1:] != x_y[:, :-1], axis=0)
+    x_y_plt = x_y[:, keep]
+
+    ax = ax or plt.subplots()[1]
+    ax.plot(x_y_plt[0, :], x_y_plt[1, :], **(plot_kwargs or {}))
+    ax.set_xlabel(channels[0])
+    ax.set_ylabel(channels[1])
+    return ax.get_figure()
+
+
+@plot_2d.register
+def _(pulse_template: PulseTemplate,
+      channels: Tuple[ChannelID, ChannelID],
+      sample_rate: float = None,
+      ax: plt.Axes = None,
+      plot_kwargs: Mapping = None,
+      parameters=None,
+      channel_mapping=None) -> plt.Figure:
+
+    if channel_mapping is None:
+        channel_mapping = {ch: ch if ch in channels else None
+                           for ch in pulse_template.defined_channels}
+    create_program_kwargs = {'channel_mapping': channel_mapping}
+    if parameters is not None:
+        create_program_kwargs['parameters'] = parameters
+
+    program = pulse_template.create_program(**create_program_kwargs)
+    return plot_2d(program, channels, sample_rate=sample_rate, ax=ax, plot_kwargs=plot_kwargs)
+
+
 class PlottingNotPossibleException(Exception):
     """Indicates that plotting is not possible because the sequencing process did not translate
     the entire given PulseTemplate structure."""