Solving AttributeError: 'float' object has no attribute 'rint'

Problem

Lately, I have been working on some ETL projects and during the transform stage I come across the error "AttributeError: 'float' object has no attribute 'rint'", combined with "TypeError: loop of ufunc does not support argument 0 of type float which has no callable rint method".

Explanation

It took a while but it became obvious that as I get/extract data from many sources (CSV, JSON, or XML), similar columns might have a mixture of the datatype (i.e a column may have a string and int data type mixed), and before I can proceed to the transform stage, I would need that column to have a designated datatype, especially if I want to perform other tasks on it (which was what I was trying to do and kept encountering the errors).

Solution

To convert the column with a mixed data type, you will need to cast it to the designated data type you intend to work with.

This can be achieved by using the pandas.DataFrame.astype function, as illustrated below

import pandas as pd

# an example of extracted data
extracted_data = pd.DataFrame({
    'Brand': ['Gucci', 'Nike', 'Adidas', 'Hermes', 'Zara'],
    'year_of_manufacture': [2010, 1999, '2012', 2011, '2008'], # mixed data type
    'price': ['4034.203', 5000.00, '7450.17567', 3023.004, '4901.32345'] # mixed data type
})

# cast specific columns to a desired data type
cast_to_type = {
    'year_of_manufacture': int,
    'price': float
    }
extracted_data = extracted_data.astype(cast_to_type)

# do the transfrom
extracted_data['price'] = extracted_data['price'].round(2)

print(extracted_data)

For Further Reading

1. pandas.DataFrame.astype function
2. Other ways to cast mixed data type in a list to a specific data type

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