[ENH] Refactor dipole visualization to invert y-axis when min_freq > max_freq

doc/whats_new.rst

@@ -31,6 +31,9 @@ Bug
 - Fix scaling and smoothing of loaded data dipoles to the GUI, by `George Dang`_
   in :gh:`892`
 
+- Refactor dipole visualization to support reversed y-axis in plot_tfr_morlet
+  for min_freq greater than max_freq, by `Abdul Samad Siddiqui`_ in :gh:`903`
+
 API
 ~~~
 - Add :func:`~hnn_core.CellResponse.spike_times_by_type` to get cell spiking times

hnn_core/tests/test_viz.py

@@ -187,6 +187,13 @@ def test_dipole_visualization(setup_net):
     # multiple TFRs get averaged
     fig = plot_tfr_morlet(dpls, freqs=np.arange(23, 26, 1.), n_cycles=3,
                           show=False)
+    # when min_freq > max_freq (y-axis inversion)
+    fig = plot_tfr_morlet(dpls, freqs=np.array([30, 20, 10]),
+                          n_cycles=3, show=False)
+    ax = fig.get_axes()[0]
+    y_limits = ax.get_ylim()
+    assert y_limits[0] > y_limits[1], \
+        "Y-axis should be inverted when min_freq > max_freq"
 
     with pytest.raises(RuntimeError,
                        match="All dipoles must be scaled equally!"):

hnn_core/viz.py

@@ -807,6 +807,11 @@ def plot_tfr_morlet(dpl, freqs, *, n_cycles=7., tmin=None, tmax=None,
     power = np.mean(trial_power, axis=0)
     im = ax.pcolormesh(times, freqs, power[0, 0, ...], cmap=colormap,
                        shading='auto')
+
+    if freqs[0] > freqs[-1]:
+        freqs = freqs[::-1]
+        ax.invert_yaxis()
+
     ax.set_xlabel('Time (ms)')
     ax.set_ylabel('Frequency (Hz)')