facet_grid throws an error: ValueError: No objects to concatenate

[vishv-jeet]

Minimum example to produce the bug using plotnine version 0.12.3

import numpy as np import polars as pl from plotnine import ggplot, geom_point, facet_grid, aes tickers = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J'] keys = ['foo', 'bar', 'baz'] periods = [i for i in range(660)] df = pl.DataFrame([(i, j, k) for i in tickers for j in keys for k in periods], ['ticker', 'key', 'period'])\ .with_columns(value=pl.Series(np.random.rand(19800)))

( ggplot(df, aes(x='period', y='value'))

• geom_point()
• facet_grid('ticker ~ key') )

""" ########################################################

File .venv/lib/python3.8/site-packages/IPython/core/formatters.py:708, in PlainTextFormatter.call(self, obj) 701 stream = StringIO() 702 printer = pretty.RepresentationPrinter(stream, self.verbose, 703 self.max_width, self.newline, 704 max_seq_length=self.max_seq_length, 705 singleton_pprinters=self.singleton_printers, 706 type_pprinters=self.type_printers, 707 deferred_pprinters=self.deferred_printers) --> 708 printer.pretty(obj) 709 printer.flush() 710 return stream.getvalue()

File .venv/lib/python3.8/site-packages/IPython/lib/pretty.py:410, in RepresentationPrinter.pretty(self, obj) 407 return meth(obj, self, cycle) 408 if cls is not object \ 409 and callable(cls.dict.get('repr')): --> 410 return _repr_pprint(obj, self, cycle) 412 return _default_pprint(obj, self, cycle) 413 finally:

File .venv/lib/python3.8/site-packages/IPython/lib/pretty.py:778, in _reprpprint(obj, p, cycle) 776 """A pprint that just redirects to the normal repr function.""" 777 # Find newlines and replace them with p.break() --> 778 output = repr(obj) 779 lines = output.splitlines() 780 with p.group():

File .venv/lib/python3.8/site-packages/plotnine/ggplot.py:114, in ggplot.repr(self) 110 def repr(self) -> str: 111 """ 112 Print/show the plot 113 """ --> 114 figure = self.draw(show=True) 116 dpi = figure.get_dpi() 117 W = int(figure.get_figwidth() * dpi)

File .venv/lib/python3.8/site-packages/plotnine/ggplot.py:224, in ggplot.draw(self, show) 222 self = deepcopy(self) 223 with plot_context(self, show=show): --> 224 self._build() 226 # setup 227 figure, axs = self._create_figure()

File .venv/lib/python3.8/site-packages/plotnine/ggplot.py:328, in ggplot._build(self) 325 layout.map_position(layers) 327 # Apply and map statistics --> 328 layers.compute_statistic(layout) 329 layers.map_statistic(self) 331 # Prepare data in geoms 332 # e.g. from y and width to ymin and ymax

File /.venv/lib/python3.8/site-packages/plotnine/layer.py:471, in Layers.compute_statistic(self, layout) 469 def compute_statistic(self, layout: Layout): 470 for l in self: --> 471 l.compute_statistic(layout)

File .venv/lib/python3.8/site-packages/plotnine/layer.py:284, in layer.compute_statistic(self, layout) 282 data = self.stat.use_defaults(data) 283 data = self.stat.setup_data(data) --> 284 data = self.stat.compute_layer(data, params, layout) 285 self.data = data

File .venv/lib/python3.8/site-packages/plotnine/stats/stat.py:306, in stat.compute_layer(cls, data, params, layout) 303 pscales = layout.get_scales(pdata["PANEL"].iat[0]) 304 return cls.compute_panel(pdata, pscales, **params) --> 306 return groupby_apply(data, "PANEL", fn)

File .venv/lib/python3.8/site-packages/plotnine/utils.py:597, in groupbyapply(df, cols, func, *args, **kwargs) 593 for , d in df.groupby(cols, observed=True): 594 # function fn should be free to modify dataframe d, therefore 595 # do not mark d as a slice of df i.e no SettingWithCopyWarning 596 lst.append(func(d, *args, **kwargs)) --> 597 return pd.concat(lst, axis=axis, ignore_index=True)

File .venv/lib/python3.8/site-packages/pandas/core/reshape/concat.py:372, in concat(objs, axis, join, ignore_index, keys, levels, names, verify_integrity, sort, copy) 369 elif copy and using_copy_on_write(): 370 copy = False --> 372 op = _Concatenator( 373 objs, 374 axis=axis, 375 ignore_index=ignore_index, 376 join=join, 377 keys=keys, 378 levels=levels, 379 names=names, 380 verify_integrity=verify_integrity, 381 copy=copy, 382 sort=sort, 383 ) 385 return op.get_result()

File .venv/lib/python3.8/site-packages/pandas/core/reshape/concat.py:429, in _Concatenator.init(self, objs, axis, join, keys, levels, names, ignore_index, verify_integrity, copy, sort) 426 objs = list(objs) 428 if len(objs) == 0: --> 429 raise ValueError("No objects to concatenate") 431 if keys is None: 432 objs = list(com.not_none(*objs))

ValueError: No objects to concatenate

"""

[has2k1]

This is a bug. The problem is the column with the name "key". For now you can change it to anything else.

[vishv-jeet]

Many thanks for the acknowledgement and the solution.VishySent from my iPhoneOn Dec 8, 2023, at 3:46 AM, Hassan Kibirige @.***> wrote: This is a bug. The problem is the column with the name "key". For now you can change it to anything else.

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