Merge branch 'main' into pylintenable8

qiskit/visualization/counts_visualization.py

@@ -343,8 +343,8 @@ def _plotting_core(
  labels_dict, all_pvalues, all_inds = _plot_data(data, labels, number_to_keep, kind=kind)
  rects = []
  for item, _ in enumerate(data):
+ label = None
  for idx, val in enumerate(all_pvalues[item]):
- label = None
  if not idx and legend:
  label = legend[item]
  if val > 0:
@@ -358,6 +358,7 @@ def _plotting_core(
  zorder=2,
  )
  )
+ label = None
  bar_center = (width / 2) * (length - 1)
  ax.set_xticks(all_inds[item] + bar_center)
  ax.set_xticklabels(labels_dict.keys(), fontsize=14, rotation=70)

releasenotes/notes/fix-plot-legend-not-showing-up-3202bec143529e49.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+ - |
+ Fixed plot legend error when your dataset has a zero value at first position.
+ When one of your counts or distributions had a zero value at first position, the relative legend didn't show up.
+ See `#10158 <https://github.com/Qiskit/qiskit-terra/issues/10158>` for more details.

test/python/visualization/test_plot_histogram.py

@@ -214,6 +214,19 @@ def test_with_number_to_keep_multiple_executions_correct_image(self):
  mpl.pyplot.close(figure_ref)
  mpl.pyplot.close(figure_truncated)
 
+ @unittest.skipUnless(optionals.HAS_MATPLOTLIB, "matplotlib not available.")
+ def test_number_of_items_in_legend_with_data_starting_with_zero(self):
+ """Test legend if there's a 0 value at the first item of the dataset"""
+ dist_1 = {"0": 0.369, "1": 0.13975}
+ dist_2 = {"0": 0, "1": 0.48784}
+ legend = ["lengend_1", "lengend_2"]
+ plot = plot_histogram([dist_1, dist_2], legend=legend)
+ self.assertEqual(
+ len(plot._localaxes[0].legend_.texts),
+ 2,
+ "Plot should have the same number of legend items as defined",
+ )
+
 
 if __name__ == "__main__":
  unittest.main(verbosity=2)