Predicting Home Rental Prices with MindsDB in Python

Predicting Home Rental Prices with MindsDB in Python


6 min read

In this tutorial, we'll will learn to create, train, and query a simple machine learning model (predictor) with Mindsdb in Python. You can check this tutorial for a more generic approach to implementing a machine learning model with MindsDB.

First, we need to set up a development environment. You will need access to a working MindsDB installation, which can be done locally or via MindsDB Cloud.

You can set up your MindsDB cloud account following this guide. Alternatively, you can set up your MindsDB locally using Docker or Python. For simplicity, we would be using MindsDB via the MindsDB cloud in this tutorial.

For this tutorial, I will be coding using VS-code. You can use other IDEs of your choice or a python environment like Jupyter Notebook. As with best practices, make sure to code within a virtual environment ( for IDEs). To save yourself the haggle of setting up a virtual environment, you can just use Jupyter Notebook.


The following are the requirements for this tutorial:

  • Python
  • Sqlalchemy
  • MindsDB (you can install using pip)
  • pymysql

With that done, let's get started.

The Data

Creating a Database

You can peruse a local data on your local machine for this. In this case, you will need to upload it to MindsDB via MindsDB SQL Editor.

Follow this guide to upload the file to MindsDB.

Alternatively, you can utilize a demo database we've already prepared for you.

To create a data connection using the demo database, you will need to create a database from within your MindsDB cloud account.

// Connecting as a database via sql CREATE DATABASE 

    WITH ENGINE = "postgres",
        "user": "demo_user",
        "password": "demo_password",
        "host": "",
        "port": "5432",
        "database": "demo"

Or if you want, you can download the demo database as a .CSV file, then upload it via MindsDB SQL editor.

Follow this guide to upload the file to MindsDB.

Once uploaded, you should be able to query the file directly.

FROM files.home_rentals

For the sake of ease, we would be creating our database from within a MindsDB Cloud Account. You can go ahead and do just that.

Connecting to the Database

Now, navigate into a working directory where you have your virtual environment setup, then create a file. To create a database connection, simply follow this guide on how to do that using Sqlachemy and pymysql.

When you are done, you should have something like this:


import mindsdb
import sqlalchemy
import pymysql
from sqlalchemy import create_engine

user = 'MindsDB Cloud Username' //your Mindsdb Cloud email address is your username
password = 'MindsDB Cloud Password' //replace this value
host = ''
port = 3306
database = 'example_db'

def get_connection():
        return create_engine(
                url="mysql+pymysql://{0}:{1}@{2}:{3}/{4}".format(user, password, host, port, database)

if __name__ == '__main__':
                engine = get_connection()
                print(f"Connection to the {host} for user {user} created successfully.")
        except Exception as ex:
                print("Connection could not be made due to the following error: \n", ex)

You can also check that your connection is successful by running the python file from your terminal using python

Connection to the for user demo_user created successfully.

The Sqlalchemy create-engine is lazy. To run further checks on your connection, you might want to run queries on the database to see if it returns some data.


with engine.connect() as eng:
    query = eng.execute("SELECT * FROM example_db.demo_data.home_rentals LIMIT 2;")

    for row in query:

On execution, you should get this printed in your terminal:

(2, 1, 917, 'great', 13, 'berkeley_hills', 3901)
(0, 1, 194, 'great', 10, 'berkeley_hills', 2042)

Getting an Sqlalchemy Operational error

While executing your code, you might get an operational error from Sqlalchemy:Lost connection to MySQL server during query ([WinError 10054] An existing connection was forcibly closed by the remote host).

This error is triggered due to an existing connection. In this case, you must close the connection before executing your next line of code. Simply call Sqlalchemy close method on the engine. For instance, eng.close()

Training a Predictor With CREATE PREDICTOR

With that done, we can now train our first machine learning predictor. For that, we are going to use the CREATE PREDICTOR syntax where we would specify what sub-query to train FROM and what we want to PREDICT.

CREATE PREDICTOR mindsdb.rental_pred
FROM example_db
  (SELECT * FROM demo_data.home_rentals)
PREDICT rental_price;

mindsdb in mindsdb.rental_pred does not reference a database. It is MindsDB standard way of creating a predictor. Alternatively, you could simply write rental_pred. However, it is advisable to use mindsdb.rental_pred to quicken response time. Slow response time could trigger Sqlachemy operational error.

Implementing this in our code:


predictor = eng.execute("CREATE PREDICTOR mindsdb.rental_pred FROM example_db (SELECT * FROM demo_data.home_rentals) PREDICT rental_price;")

Checking the Status of a Predictor

It might take a couple of minutes to train a predictor. You can monitor the status of your predictor using this line of code:

result = eng.execute("SELECT status FROM mindsdb.predictors WHERE name='rental_pred';")
        for i in result:

If the training is complete, you should get this printed in your terminal:


Once the status reads complete, we can start making predictions!

Making Predictions

Make Predictions with SELECT

Now, we can make predictions by querying the predictor. The SELECT syntax allows you make predictions for the label based on the chosen features.

predict  = eng.execute("SELECT rental_price, rental_price_explain FROM mindsdb.home_rentals_model WHERE number_of_bathrooms=2 AND sqft=1000;")

        for i in predict:

On execution, you should get this printed in your terminal:

('4770', '{"predicted_value": 4770, "confidence": 0.99, "anomaly": null, "truth": null, "confidence_lower_bound": 4689, "confidence_upper_bound": 4852}') 

<!-- rental_price = "4770", rental_price_explain= '{"predicted_value":4770, ...}... -->

Make Batch Predictions with JOIN

You might also want to make bulk predictions on several records in your table. In that case, you can achieve that by joining the table containing the data (example_db.demo_data.home_rentals) to your predictor.


from sqlalchemy import text


bulk = text("SELECT t.rental_price AS real_price, m.rental_price_explain AS predicted_price, t.number_of_rooms,  t.number_of_bathrooms, t.sqft, t.location, t.days_on_market FROM example_db.demo_data.home_rentals AS t JOIN mindsdb.home_rentals_model AS m LIMIT 100;")

batch = eng.execute(bulk)

    for i in batch:

On execution, you should get this printed in your terminal:

(3901, 2, 1, 917, 'great', 13, '{"predicted_value": 3886, "confidence": 0.99, "anomaly": null, "truth": null, "confidence_lower_bound": 3805, "confidence_upper_bound": 3967}')
(2042, 0, 1, 194, 'great', 10, '{"predicted_value": 2007, "confidence": 0.99, "anomaly": null, "truth": null, "confidence_lower_bound": 1925, "confidence_upper_bound": 2088}')
(1871, 1, 1, 543, 'poor', 18, '{"predicted_value": 1865, "confidence": 0.99, "anomaly": null, "truth": null, "confidence_lower_bound": 1783, "confidence_upper_bound": 1946}')
(3026, 2, 1, 503, 'good', 10, '{"predicted_value": 3020, "confidence": 0.99, "anomaly": null, "truth": null, "confidence_lower_bound": 2938, "confidence_upper_bound": 3101}')

What's Next?

Have fun while trying it out yourself!

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