Plotting fails on branches all filled with the same value

[davehadley]

On latest pypi version uproot-browser 0.4.0 when plotting branches all filled with the same value I see the error message:

╭────────────────────────────────────────────────────────────────────────────────────────────── Traceback (most recent call last) ──────────────────────────────────────────────────────────────────────────────────────────────╮
│                                                                                                                                                                                                                               │
│ /storage/epp2/phskaj/t2k/ncfgd/2022-03-01/ncfgd/env/ncfgd/lib/python3.8/site-packages/uproot_browser/plot_view.py:55 in __rich_console__                                                                                      │
│                                                                                                                                                                                                                               │
│    54 │   │   try:                                                                                                                                                                                                            │
│ ❱  55 │   │   │   canvas = make_plot(self.item, width, height)                                                                                                                                                                │
│    56 │   │   │   yield rich.text.Text.from_ansi(canvas)                                                                                                                                                                      │
│ /storage/epp2/phskaj/t2k/ncfgd/2022-03-01/ncfgd/env/ncfgd/lib/python3.8/site-packages/uproot_browser/plot_view.py:40 in make_plot                                                                                             │
│                                                                                                                                                                                                                               │
│    39 │   plt.plotsize(*size)                                                                                                                                                                                                 │
│ ❱  40 │   uproot_browser.plot.plot(item)                                                                                                                                                                                      │
│    41 │   return plt.build()                                                                                                                                                                                                  │
│                                                                                                                                                                                                                               │
│ /storage/epp2/phskaj/t2k/ncfgd/2022-03-01/ncfgd/env/ncfgd/lib/python3.8/functools.py:875 in wrapper                                                                                                                           │
│                                                                                                                                                                                                                               │
│   874 │   │                                                                                                                                                                                                                   │
│ ❱ 875 │   │   return dispatch(args[0].__class__)(*args, **kw)                                                                                                                                                                 │
│   876                                                                                                                                                                                                                         │
│                                                                                                                                                                                                                               │
│ /storage/epp2/phskaj/t2k/ncfgd/2022-03-01/ncfgd/env/ncfgd/lib/python3.8/site-packages/uproot_browser/plot.py:58 in plot_branch                                                                                                │
│                                                                                                                                                                                                                               │
│   57 │   finite = values[np.isfinite(values)]                                                                                                                                                                                 │
│ ❱ 58 │   histogram: hist.Hist = hist.numpy.histogram(finite, bins=100, histogram=hist.Hist)                                                                                                                                   │
│   59 │   plt.bar(histogram.axes[0].centers, histogram.values().astype(float))                                                                                                                                                 │
│                                                                                                                                                                                                                               │
│ /storage/epp2/phskaj/t2k/ncfgd/2022-03-01/ncfgd/env/ncfgd/lib/python3.8/site-packages/boost_histogram/numpy.py:166 in histogram                                                                                               │
│                                                                                                                                                                                                                               │
│   165 │                                                                                                                                                                                                                       │
│ ❱ 166 │   result = histogramdd(                                                                                                                                                                                               │
│   167 │   │   (a,),                                                                                                                                                                                                           │
│                                                                                                                                                                                                                               │
│ /storage/epp2/phskaj/t2k/ncfgd/2022-03-01/ncfgd/env/ncfgd/lib/python3.8/site-packages/boost_histogram/numpy.py:78 in histogramdd                                                                                              │
│                                                                                                                                                                                                                               │
│    77 │   │   │   │   r = (np.amin(a[n]), np.amax(a[n]))                                                                                                                                                                      │
│ ❱  78 │   │   │   cpp_ax = _core.axis.regular_numpy(b, r[0], r[1])                                                                                                                                                            │
│    79 │   │   │   new_ax = _cast(None, cpp_ax, _axis.Axis)                                                                                                                                                                    │
╰───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
ValueError: range of axis is zero

so I guess that some special behaviour is needed for the case where the min and max of the value being plotted are the same.

BTW this looks like a great project, thank you. :)

[henryiii]

scikit-hep/boost-histogram#721

Though a bh release might not be rushed out, so might patch it here too for now.