This is the first part of the Machine Learning series. For your convenience you can find other parts using the links below (or by guessing the address):
Part 1 — Linear regression in MXNet
Part 2 — Linear regression in SQL
Part 3 — Linear regression in SQL revisited
Part 4 — Linear regression in T-SQL
Part 5 — Linear regression
Part 6 — Matrix multiplication in SQL
Part 7 — Forward propagation in neural net in SQL
Part 8 — Backpropagation in neural net in SQL

In this series I assume you do know basics of machine learning. I will provide some source code for different use cases but no extensive explanation. Let’s go.

Today we will take a look at linear regression in MXNet. We will predict sepal length in well know iris dataset.

I assume you have the dataset uploaded to s3. Let’s go with loading the dataset:

We can see some records with print df.head(3) or check different iris categories with df.iris.unique().

We have one target variable and four features. Let’s create two adttional:

Two features similar to one hot encoding of categorical feature.

Time to prepare training and test datasets with: df_train, df_test = train_test_split( df, test_size=0.3, random_state=1)

Let’s get down to training. We start with defining the training variables and the target one:

Let’s prepare class representing data instance:

We initialize parameters and attach gradient calculation. This is a very nice feature, we don’t need to take care of derivatives, everything is taken care for us.

Let’s now carry on with a single step for gradient:

We just subtract gradient multiplied by learning rate. Also, we use x[:] instead of x to avoid reinitializing the gradient. If we go with the latter, we will see the following error:

Now, let’s train our model:

We should get the following:

Training - mean

Note that our loss uses mean whereas we could calculate just a sum. However, due to overflow problems we would get the following:

Training - sum

Finally, let’s check the performance of trained model:

Done.

Summary

We can see that linear regression is pretty concise and easy. However, this uses Python and Spark which me might want to avoid. In next parts we will take a look at different solutions.