Keyerror: ‘key of type tuple not found and not a multiindex’

Key Error: ‘Key of type tuple not found and not a MultiIndex’

The error message “KeyError: ‘Key of type tuple not found and not a MultiIndex'” occurs when you try to access a value from a dictionary using a key that is a tuple, and that key is not found in the dictionary. Additionally, this error can also occur when using a tuple as a key to access a value from a pandas DataFrame or Series, where the tuple represents a multi-index.

Let’s break down the error and understand it in more detail with examples.

Example 1: Accessing a value from a dictionary using a tuple key

    
      # Create a dictionary
      my_dict = {('key1', 'key2'): 'value'}

      # Access value using a tuple key that exists in the dictionary
      print(my_dict[('key1', 'key2')])  # Output: 'value'

      # Access value using a tuple key that does not exist in the dictionary
      print(my_dict[('key3', 'key4')])  # KeyError: ('key3', 'key4')
    
  

In this example, we have a dictionary my_dict. We can access the value associated with a key by using square brackets notation []. When we try to access a value using a tuple key that exists in the dictionary, it works fine. However, if the tuple key does not exist in the dictionary, a KeyError is raised.

Example 2: Accessing a value from a pandas DataFrame using a tuple as a multi-index

    
      import pandas as pd

      # Create a DataFrame with a multi-index
      df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]}, index=[('x', 1), ('y', 2), ('z', 3)])

      # Access value using a tuple as a multi-index that exists in the DataFrame
      print(df.loc[('y', 2)])  # Output: A    2, B    5

      # Access value using a tuple as a multi-index that does not exist in the DataFrame
      print(df.loc[('a', 1)])  # KeyError: ('a', 1)
    
  

In this example, we have a pandas DataFrame df with a multi-index consisting of tuples. We can access a value in the DataFrame using the loc accessor and specifying the tuple as the index value. When accessing a value using a tuple that exists as a multi-index, it works correctly. However, if the tuple does not exist in the multi-index, a KeyError is raised.

To fix the ‘KeyError: ‘Key of type tuple not found and not a MultiIndex” error, you can do the following:

• Make sure the tuple key exists in the dictionary before accessing it.
• Ensure that the tuple used for accessing a value corresponds to a valid multi-index in the DataFrame.

Double-checking the keys or indices used while accessing values from dictionaries or pandas DataFrames is crucial to prevent this error.