[FIXED] FutureWarning: Using a non-tuple sequence for multidimensional indexing is deprecated use `arr[tuple(seq)]`

Issue

I have searched S/O but I couldn't find a answer for this.

When I try to plot a distribution plot using seaborn I am getting a futurewarning. I was wondering what could be the issue here.

import pandas as pd
import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt
% matplotlib inline
from sklearn import datasets

iris = datasets.load_iris()
df = pd.DataFrame(iris.data, columns=iris.feature_names)
df['class'] = iris.target
df['species'] = df['class'].map({idx:s for idx, s in enumerate(iris.target_names)})


fig, ((ax1,ax2),(ax3,ax4))= plt.subplots(2,2, figsize =(13,9))
sns.distplot(a = df.iloc[:,0], ax=ax1)
sns.distplot(a = df.iloc[:,1], ax=ax2)
sns.distplot(a = df.iloc[:,2], ax=ax3)
sns.distplot(a = df.iloc[:,3], ax=ax4)
plt.show()

This is the warning:

C:\ProgramData\Anaconda3\lib\site-packages\scipy\stats\stats.py:1713:
FutureWarning: Using a non-tuple sequence for multidimensional indexing is deprecated; 
use `arr[tuple(seq)]` instead of `arr[seq]`. 
In the future this will be interpreted as an array index, `arr[np.array(seq)]`,
which will result either in an error or a different result.
return np.add.reduce(sorted[indexer] * weights, axis=axis) / sumval

Any help? You can run the above code. You'll get the warning.

Pandas : 0.23.4, seaborn : 0.9.0, matplotlib : 2.2.3, scipy : 1.1.0, numpy: 1.15.0'

Solution

A fuller traceback would be nice. My guess is that seaborn.distplot is using scipy.stats to calculate something. The error occurs in

def _compute_qth_percentile(sorted, per, interpolation_method, axis):
    ....
    indexer = [slice(None)] * sorted.ndim
    ...
    indexer[axis] = slice(i, i + 2)
    ...
    return np.add.reduce(sorted[indexer] * weights, axis=axis) / sumval

So in this last line, the list indexer is used to slice sorted.

In [81]: x = np.arange(12).reshape(3,4)
In [83]: indexer = [slice(None), slice(None,2)]
In [84]: x[indexer]
/usr/local/bin/ipython3:1: FutureWarning: Using a non-tuple sequence for multidimensional indexing is deprecated; use `arr[tuple(seq)]` instead of `arr[seq]`. In the future this will be interpreted as an array index, `arr[np.array(seq)]`, which will result either in an error or a different result.
  #!/usr/bin/python3
Out[84]: 
array([[0, 1],
       [4, 5],
       [8, 9]])
In [85]: x[tuple(indexer)]
Out[85]: 
array([[0, 1],
       [4, 5],
       [8, 9]])

Using a list of slices works, but the plan is to depreciate in the future. Indexes that involve several dimensions are supposed to be tuples. The use of lists in the context is an older style that is being phased out.

So the scipy developers need to fix this. This isn't something end users should have to deal with. But for now, don't worry about the futurewarning. It doesn't affect the calculations or plotting. There is a way of suppressing future warnings, but I don't know it off hand.

FutureWarning: Using a non-tuple sequence for multidimensional indexing is deprecated use `arr[tuple(seq)]` instead of `arr[seq]`

Answered By - hpaulj