Seaborn Violin plot error No loop for unfunc add

Question

I'm trying to plot a violin plot with a split based on Sex ( like in the fourth example in the doccumentation but with Sex)

I can produce a categorical scatter plot and split it by Sex. However, when i attempt the same but as a violin plot; it throws an error.

Traceback (most recent call last):

  File "<ipython-input-868-0599b976fd6c>", line 1, in <module>
    sns.catplot(x="Batch", y="Age", hue = 'Sex', data = ages,  kind='violin')

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/categorical.py", line 3755, in catplot
    g.map_dataframe(plot_func, x, y, hue, **plot_kws)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/axisgrid.py", line 820, in map_dataframe
    self._facet_plot(func, ax, args, kwargs)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/axisgrid.py", line 838, in _facet_plot
    func(*plot_args, **plot_kwargs)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/categorical.py", line 2387, in violinplot
    color, palette, saturation)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/categorical.py", line 564, in __init__
    self.estimate_densities(bw, cut, scale, scale_hue, gridsize)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/categorical.py", line 679, in estimate_densities
    kde, bw_used = self.fit_kde(kde_data, bw)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/seaborn/categorical.py", line 719, in fit_kde
    kde = stats.gaussian_kde(x)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/scipy/stats/kde.py", line 208, in __init__
    self.set_bandwidth(bw_method=bw_method)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/scipy/stats/kde.py", line 540, in set_bandwidth
    self._compute_covariance()

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/scipy/stats/kde.py", line 551, in _compute_covariance
    aweights=self.weights))

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/numpy/lib/function_base.py", line 2427, in cov
    avg, w_sum = average(X, axis=1, weights=w, returned=True)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/numpy/lib/function_base.py", line 419, in average
    scl = wgt.sum(axis=axis, dtype=result_dtype)

  File "/home/tasty/anaconda3/lib/python3.7/site-packages/numpy/core/_methods.py", line 36, in _sum
    return umr_sum(a, axis, dtype, out, keepdims, initial)

TypeError: No loop matching the specified signature and casting
was found for ufunc add

My code is:

>>> print(ages.head())
            Age     Sex  Batch
PassengerId                   
852          74    male  Train
86           33  female  Train
161          44    male  Train
812          39    male  Train
837          21    male  Train

>>> sns.catplot(x="Batch", y="Age", hue = 'Sex', data = ages,  kind='violin')

Removing the kind argument produces the following scatterplot:

How do I get rid of the error to display the data as a violin plot?

Thanks in advance

edit: Seaborn version: 0.9.0 Numpy version: 1.16.2 Python version: 3.7.3

Answer 1

I had tried the suggestion from @foxthatruns's answer to no avail. I found that changing my numeric column to float64 solved the problem (reference).

df['my_column']=df['my_column'].astype('float64')

This was done with Python 3.7, seaborn 0.9.0, numpy 1.16.4.

Answer 2

I ran into the same error in a different context. Maybe this will help debugging? I was trying to show a vertical violin plot with a continuous vs categorical comparison. I produced the same error when I put the categorical variable in the y argument and also set orient='v'. Obviously this doesn't make sense. I fixed it by swapping the arguments. Maybe there's a hidden orientation issue? Try forcing the orientation? seaborn.violinplot(x='Batch', y='Age', hue='Sex', data=ages, orient='v')