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histplot doesn't accept a column with mixed data types #3846

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histplot doesn't accept a column with mixed data types#3846
@Foundsheep

Description

@Foundsheep
Foundsheep
opened on Apr 30, 2025

Issue

❌ sns.histplot(df, x=col, hue=y) throws an error when df[col] has mixed data types.
✔️ sns.histplot(df.astype(str), x=col, hue=y) works fine.

Background

  • pandas converts all columns to an 'object'-dtyped column if they have mixed data types, such as int and str.
  • However, if such a column exists, that column cannot be drawn in a histogram due to the co-existence of seemingly int and str.
  • For example, my data has a column like [0, 1, "a", "b" ... "e"].
  • Its column has object dtype, but values like 0 and 1 stay as int and it seems like the conflict between the dtypes is causing the error

Traceback

ValueError                                Traceback (most recent call last)
File lib.pyx:2391, in pandas._libs.lib.maybe_convert_numeric()

ValueError: Unable to parse string "SGAFC590DP"

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
Cell In[717], [line 5](vscode-notebook-cell:?execution_count=717&line=5)
      [3](vscode-notebook-cell:?execution_count=717&line=3) for col in df_spatter.columns:
      [4](vscode-notebook-cell:?execution_count=717&line=4)     plt.figure(figsize=(10, 10))
----> [5](vscode-notebook-cell:?execution_count=717&line=5)     sns.histplot(df_spatter, x=col, hue=y_spatter)
      [6](vscode-notebook-cell:?execution_count=717&line=6)     plt.xticks(rotation=90)
      [7](vscode-notebook-cell:?execution_count=717&line=7)     plt.show()

File c:\Users\msi\Desktop\workspace\041_HM_platform\01_src\01_work\proj_hm_process_result\.venv_hm_result\lib\site-packages\seaborn\distributions.py:1416, in histplot(data, x, y, hue, weights, stat, bins, binwidth, binrange, discrete, cumulative, common_bins, common_norm, multiple, element, fill, shrink, kde, kde_kws, line_kws, thresh, pthresh, pmax, cbar, cbar_ax, cbar_kws, palette, hue_order, hue_norm, color, log_scale, legend, ax, **kwargs)
   [1405](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1405) estimate_kws = dict(
   [1406](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1406)     stat=stat,
   [1407](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1407)     bins=bins,
   (...)
   [1411](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1411)     cumulative=cumulative,
   [1412](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1412) )
   [1414](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1414) if p.univariate:
-> [1416](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1416)     p.plot_univariate_histogram(
   [1417](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1417)         multiple=multiple,
   [1418](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1418)         element=element,
   [1419](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1419)         fill=fill,
   [1420](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1420)         shrink=shrink,
   [1421](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1421)         common_norm=common_norm,
   [1422](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1422)         common_bins=common_bins,
   [1423](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1423)         kde=kde,
   [1424](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1424)         kde_kws=kde_kws,
   [1425](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1425)         color=color,
   [1426](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1426)         legend=legend,
   [1427](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1427)         estimate_kws=estimate_kws,
   [1428](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1428)         line_kws=line_kws,
   [1429](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1429)         **kwargs,
   [1430](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1430)     )
   [1432](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1432) else:
   [1434](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1434)     p.plot_bivariate_histogram(
   [1435](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1435)         common_bins=common_bins,
   [1436](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1436)         common_norm=common_norm,
   (...)
   [1446](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1446)         **kwargs,
   [1447](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:1447)     )

File c:\Users\msi\Desktop\workspace\041_HM_platform\01_src\01_work\proj_hm_process_result\.venv_hm_result\lib\site-packages\seaborn\distributions.py:427, in _DistributionPlotter.plot_univariate_histogram(self, multiple, element, fill, common_norm, common_bins, shrink, kde, kde_kws, color, legend, line_kws, estimate_kws, **plot_kws)
    [424](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:424) histograms = {}
    [426](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:426) # Do pre-compute housekeeping related to multiple groups
--> [427](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:427) all_data = self.comp_data.dropna()
    [428](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:428) all_weights = all_data.get("weights", None)
    [430](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/distributions.py:430) multiple_histograms = set(self.variables) - {"x", "y"}

File c:\Users\msi\Desktop\workspace\041_HM_platform\01_src\01_work\proj_hm_process_result\.venv_hm_result\lib\site-packages\seaborn\_base.py:1000, in VectorPlotter.comp_data(self)
    [995](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:995) if var in self.var_levels:
    [996](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:996)     # TODO this should happen in some centralized location
    [997](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:997)     # it is similar to GH2419, but more complicated because
    [998](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:998)     # supporting `order` in categorical plots is tricky
    [999](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:999)     orig = orig[orig.isin(self.var_levels[var])]
-> [1000](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:1000) comp = pd.to_numeric(converter.convert_units(orig)).astype(float)
   [1001](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:1001) transform = converter.get_transform().transform
   [1002](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/seaborn/_base.py:1002) parts.append(pd.Series(transform(comp), orig.index, name=orig.name))

File c:\Users\msi\Desktop\workspace\041_HM_platform\01_src\01_work\proj_hm_process_result\.venv_hm_result\lib\site-packages\pandas\core\tools\numeric.py:232, in to_numeric(arg, errors, downcast, dtype_backend)
    [230](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:230) coerce_numeric = errors not in ("ignore", "raise")
    [231](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:231) try:
--> [232](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:232)     values, new_mask = lib.maybe_convert_numeric(  # type: ignore[call-overload]
    [233](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:233)         values,
    [234](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:234)         set(),
    [235](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:235)         coerce_numeric=coerce_numeric,
    [236](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:236)         convert_to_masked_nullable=dtype_backend is not lib.no_default
    [237](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:237)         or isinstance(values_dtype, StringDtype)
    [238](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:238)         and not values_dtype.storage == "pyarrow_numpy",
    [239](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:239)     )
    [240](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:240) except (ValueError, TypeError):
    [241](file:///C:/Users/msi/Desktop/workspace/041_HM_platform/01_src/01_work/proj_hm_process_result/.venv_hm_result/lib/site-packages/pandas/core/tools/numeric.py:241)     if errors == "raise":

File lib.pyx:2433, in pandas._libs.lib.maybe_convert_numeric()

ValueError: Unable to parse string "SGAFC590DP" at position 8

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