Why am I Getting a \'Pandas Hashtable KeyError\' When Accessing a DataFrame Column?

"Error: Pandas Hashtable KeyError" Troubleshooting

When attempting to retrieve a particular column from a pandas DataFrame, you may encounter a "hashtable keyerror." This error occurs when the specified column name does not exist in the DataFrame.

Investigation:

Begin by verifying the actual column names in the DataFrame. Use the following code to list the column names, ensuring that you remove any leading or trailing whitespaces:

print(reviews_new.columns.tolist())

Potential Solutions:

1. Whitespace in Column Names

If the column names contain whitespaces, you can:

• Strip whitespaces from column names:

  reviews_new.columns = reviews_new.columns.str.strip()

• Use skipinitialspace when reading the CSV file:

  reviews_new = pd.read_csv("D:\aviva.csv", skipinitialspace=True)

2. Custom Separator

If the CSV file uses a separator other than the default comma (,), you need to specify it using the sep parameter:

• Semicolon as separator:

  reviews_new = pd.read_csv("D:\aviva.csv", sep=';')

• Whitespace as separator:

  # sep is whitespace
  reviews_new = pd.read_csv("D:\aviva.csv", sep='\s+')
  
  # Another option for whitespaces as separator
  reviews_new = pd.read_csv("D:\aviva.csv", delim_whitespace=True)

3. Missing Column Names

If the DataFrame does not have column names, the following code will retrieve the column values using the DataFrame index:

print(df.index)
print(df.index.get_level_values('column_name'))

Additional Notes:

• For DataFrames with multiple indices (MultiIndex), use get_level_values to retrieve column values by level name.
• Ensure that the specified column name matches the exact case and capitalization of the column in the DataFrame.

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