[FIXED] KeyError: 46220

Issue

edited to address the comments

1. added lines at the beginning where the data was imported from MNIST
2. added the full error message from jupyter notebook as text

I am trying to implement a very simple code in python (jupyter notebook, if it matters):

    from sklearn.datasets import fetch_openml
    x, y = fetch_openml('mnist_784', version=1, return_X_y=True, data_home='./data/')
    y = y.astype(int)

fig, ax = plt.subplots(2, 4, figsize=(20, 8))
for a in ax.ravel():
    j = np.random.choice(len(y))
    sns.heatmap(x[j].reshape(28,28), ax=a, cbar=False, cmap='gray_r')
    a.set_title(f'Label: {y[j]}')
    a.set_xticks([])
    a.set_yticks([])

and I get the following error shown in the screenshot. I don't think this is a code problem, as this was taken directly from the lecturer's notes. Could anyone help me troubleshoot and enlighten me, please?

See error message below:

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   3079             try:
-> 3080                 return self._engine.get_loc(casted_key)
   3081             except KeyError as err:

pandas/_libs/index.pyx in 
pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/index.pyx in 
pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/hashtable_class_helper.pxi in 
pandas._libs.hashtable.PyObjectHashTable.get_item()

pandas/_libs/hashtable_class_helper.pxi in 
pandas._libs.hashtable.PyObjectHashTable.get_item()

KeyError: 46220

The above exception was the direct cause of the following exception:

KeyError                                  Traceback (most recent call last)
<ipython-input-6-02155e9f4730> in <module>
      2 for a in ax.ravel():
      3     j = np.random.choice(len(y))
----> 4     sns.heatmap(x[j].reshape(28,28), ax=a, cbar=False, cmap='gray_r')
      5     a.set_title(f'Label: {y[j]}')
      6     a.set_xticks([])

~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/frame.py in __getitem__(self, key)
   3022             if self.columns.nlevels > 1:
   3023                 return self._getitem_multilevel(key)
-> 3024             indexer = self.columns.get_loc(key)
   3025             if is_integer(indexer):
   3026                 indexer = [indexer]

~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   3080                 return self._engine.get_loc(casted_key)
   3081             except KeyError as err:
-> 3082                 raise KeyError(key) from err
   3083 
   3084         if tolerance is not None:

KeyError: 46220

KeyError: 46220

Solution

I suppose that with the line below you were trying to access the row j of the pandas DataFrame x:

sns.heatmap(x[j].reshape(28,28), ax=a, cbar=False, cmap='gray_r')

However in order to access the values of a row by name you should use x.iloc[j].values instead. Lots of examples can be found here.

The complete code is:

from sklearn.datasets import fetch_openml
import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt

x, y = fetch_openml('mnist_784', version=1, return_X_y=True, data_home='./data/')
y = y.astype(int)

fig, ax = plt.subplots(2, 4, figsize=(20, 8))
for a in ax.ravel():
    j = np.random.choice(len(y))
    sns.heatmap(x.iloc[j].values.reshape(28,28), ax=a, cbar=False, cmap='gray_r')
    a.set_title(f'Label: {y[j]}')
    a.set_xticks([])
    a.set_yticks([])

The result produced:

Answered By - ClaudiaR