df.hvplot.bar() raises if hover_cols is provided while plotting multiple columns

[stuarteberg]

In df.hvplot.bar(), the hover_cols parameter cannot be used if more than one column is being plotted. In fact, it fails any time a list of columns provided, even if that list contains only one element.

Example:

import pandas as pd
import hvplot.pandas

data = [
    [10, 20, 'hello'],
    [20, 10, 'goodbye']
]
df = pd.DataFrame(data, columns=['a', 'b', 'c'])

# Working
df.hvplot.bar(y='a', hover_cols=['c'])

# Broken
df.hvplot.bar(y=['a'], hover_cols=['c'])
df.hvplot.bar(y=['a', 'b'], hover_cols=['c'])

The error is:

DataError: Supplied data does not contain specified dimensions, the following dimensions were not found: ['c']

Click here for Traceback

---------------------------------------------------------------------------
DataError                                 Traceback (most recent call last)
/tmp/ipykernel_1145701/4271017800.py in <module>
     12 
     13 # Broken
---> 14 df.hvplot.bar(y=['a'], hover_cols=['c'])
     15 df.hvplot.bar(y=['a', 'b'], hover_cols=['c'])

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/hvplot/plotting/core.py in bar(self, x, y, **kwds)
    919         - Wiki: https://en.wikipedia.org/wiki/Bar_chart
    920         """
--> 921         return self(x, y, kind="bar", **kwds)
    922 
    923     def barh(self, x=None, y=None, **kwds):

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/hvplot/plotting/core.py in __call__(self, x, y, kind, **kwds)
    128                 return pn.panel(plot, **panel_dict)
    129 
--> 130         return self._get_converter(x, y, kind, **kwds)(kind, x, y)
    131 
    132     def _get_converter(self, x=None, y=None, kind=None, **kwds):

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/hvplot/converter.py in __call__(self, kind, x, y)
   1226                         dataset = Dataset(data)
   1227                     dataset = dataset.redim(**self._redim)
-> 1228                 obj = method(x, y)
   1229                 obj._dataset = dataset
   1230 

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/hvplot/converter.py in bar(self, x, y, data)
   1697             y = y[0] if isinstance(y, (list, tuple)) else y
   1698             return self.single_chart(Bars, x, y, data)
-> 1699         return self._category_plot(Bars, x, list(y), data)
   1700 
   1701     def barh(self, x=None, y=None, data=None):

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/hvplot/converter.py in _category_plot(self, element, x, y, data)
   1687             obj = Dataset(df, kdims, vdims).to(element, x).layout()
   1688         else:
-> 1689             obj = element(df, kdims, vdims)
   1690         return (obj.redim(**self._redim).relabel(**self._relabel)
   1691                 .apply(self._set_backends_opts, cur_opts=cur_opts, compat_opts=compat_opts))

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/holoviews/element/selection.py in __init__(self, *args, **kwargs)
     21 
     22     def __init__(self, *args, **kwargs):
---> 23         super().__init__(*args, **kwargs)
     24         self._index_skip = False
     25 

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/holoviews/element/chart.py in __init__(self, data, kdims, vdims, **params)
     49         if len(params.get('kdims', [])) == self._max_kdim_count + 1:
     50             self.param.warning('Chart elements should only be supplied a single kdim')
---> 51         super().__init__(data, **params)
     52 
     53     def __getitem__(self, index):

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/holoviews/core/data/__init__.py in __init__(self, data, kdims, vdims, **kwargs)
    340         (data, self.interface, dims, extra_kws) = initialized
    341         super(Dataset, self).__init__(data, **dict(kwargs, **dict(dims, **extra_kws)))
--> 342         self.interface.validate(self, validate_vdims)
    343 
    344         # Handle _pipeline property

/groups/flyem/proj/cluster/miniforge/envs/flyem/lib/python3.7/site-packages/holoviews/core/data/pandas.py in validate(cls, dataset, vdims)
    155             raise DataError("Supplied data does not contain specified "
    156                             "dimensions, the following dimensions were "
--> 157                             "not found: %s" % repr(not_found), cls)
    158 
    159 

DataError: Supplied data does not contain specified dimensions, the following dimensions were not found: ['c']

PandasInterface expects tabular data, for more information on supported datatypes see http://holoviews.org/user_guide/Tabular_Datasets.html

Software versions

$ conda list | grep -E 'holoviews|hvplot|bokeh|cpython'
bokeh                     2.4.3            py37h89c1867_0    conda-forge
holoviews                 1.15.0             pyhd8ed1ab_0    conda-forge
hvplot                    0.8.1              pyhd8ed1ab_0    conda-forge
jupyter_bokeh             3.0.2              pyhd8ed1ab_0    conda-forge
python                    3.7.12          hb7a2778_100_cpython    conda-forge

[maximlt]

I can reproduce.