B4J Tutorial [PyBridge] Linear regression with scikit learn

This example is based on: https://scikit-learn.org/stable/auto_examples/linear_model/plot_ols.html
The steps are:

1. Read the CSV file with StringUtils.
2. Take the BMI and target columns.
3. Split the data to train and test sets.
4. Train the model with a call to LinearRegression.fit.
5. Evaluate the model using the test data set.
6. Plot it using MatplotLib.

I also added a step where the plot is fetched back to B4J and displayed with a B4XImageView. You can instead call plot.run("show") to show the standard plot window (which has advantages over a static image).

Note that the regression will work better with all inputs, instead of just the BMI. You can test it by adding all fields to "BMI":

For Each row() As String In data
    Dim x As List
    x.Initialize
    For i = 0 To row.Length - 2 'the last column is the target
        x.Add(row(i).As(Double))
    Next
    bmi.Add(x) 'the X input is expected to be a list of arrays.
    target.Add(row(10).As(Double))
Next

And skip the plotting code.

Don't miss the dependencies line at the top.

 

[stevel05]

The Objects/python folder is not included in the zip file. Is it intended that we set this up after unzipping? Or an oversight?

 

[Erel]

Good point. It is intended as it will make the zip very large.

You can make a copy of an existing python folder or change this line to point to an existing Python runtime:

Dim opt As PyOptions = Py.CreateOptions(File.Combine(File.DirApp, "Python/python/python.exe"))

In both cases you need to then install the dependencies if not already installed.

'dependencies: pip install scikit-learn matplotlib

 

[stevel05]

OK. Thanks. I find that getting the environment right is one of the most difficult things about using python. I certainly don't want one big environment, and also don't want 100 that are identical. It will take some figuring out.

 

[stevel05]

in the future, It might be worth considering adding an option in the IDE to copy a new python environment to the project if it doesn't exist.

 

[Erel]

For now:

1. New Project - PyBridge With Python
2. Ctrl + Click the python shell link at the top.
3. Write: pip install scikit-learn matplotlib
Wait for it to complete and close the window.
4. Move the Objects\Python to the existing project Objects folder.