Elastic Net regularization in ML Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the ElasticNet model from scikit-learn.

ML Python

from sklearn.linear_model import [1]

Drag options to blanks, or click blank then click option'

AElasticNet

BLinearRegression

CLogisticRegression

DRidge

Attempts:

3 left

💡 Hint

Common Mistakes

Importing LinearRegression instead of ElasticNet.

Confusing ElasticNet with LogisticRegression.

The ElasticNet model is imported from sklearn.linear_model using ElasticNet.

2fill in blank

medium

Complete the code to create an ElasticNet model with alpha set to 0.5.

ML Python

model = ElasticNet([1]=0.5)

Drag options to blanks, or click blank then click option'

Aalpha

Bmax_iter

Cl1_ratio

Dfit_intercept

Attempts:

3 left

💡 Hint

Common Mistakes

Using l1_ratio instead of alpha for regularization strength.

Setting max_iter instead of alpha.

The alpha parameter controls the overall strength of regularization in ElasticNet.

3fill in blank

hard

Fix the error in the code to fit the ElasticNet model on training data X_train and y_train.

ML Python

model = ElasticNet(alpha=0.1, l1_ratio=0.7)
model.[1](X_train, y_train)

Drag options to blanks, or click blank then click option'

Ascore

Bfit

Ctransform

Dpredict

Attempts:

3 left

💡 Hint

Common Mistakes

Using predict instead of fit to train the model.

Using transform which is not available for ElasticNet.

The fit method trains the model on the given data.

4fill in blank

hard

Fill both blanks to create a dictionary of coefficients and intercept from the trained ElasticNet model.

ML Python

model = ElasticNet(alpha=0.2, l1_ratio=0.5).fit(X, y)
result = {"coefficients": model.[1], "intercept": model.[2]

Drag options to blanks, or click blank then click option'

Acoef_

Bintercept_

Cfit

Dpredict

Attempts:

3 left

💡 Hint

Common Mistakes

Using fit or predict instead of coef_ or intercept_.

Confusing attribute names without underscores.

The trained model stores coefficients in coef_ and intercept in intercept_.

5fill in blank

hard

Fill all three blanks to compute the mean squared error (MSE) of ElasticNet predictions on test data.

ML Python

from sklearn.metrics import {{BLANK_1 }}
predictions = model.predict(X_test)
mse = [2](y_test, {{BLANK_3}})

Drag options to blanks, or click blank then click option'

Amean_squared_error

Bpredictions

Cy_test

Dr2_score

Attempts:

3 left

💡 Hint

Common Mistakes

Using r2_score instead of mean_squared_error.

Swapping true and predicted values in the function.

We import mean_squared_error to measure error. The function takes true values y_test and predicted values predictions.

Practice

1. What is the main purpose of Elastic Net regularization in machine learning?

easy

A. To only use L1 penalty for feature selection

B. To increase the number of features in the model

C. To combine L1 and L2 penalties for better feature selection and stability

D. To remove all regularization from the model

Solution

1. Step 1: Understand Elastic Net components

   Elastic Net combines L1 (lasso) and L2 (ridge) penalties to balance feature selection and coefficient shrinkage.

2. Step 2: Identify the purpose

   This combination helps select important features while keeping the model stable and avoiding overfitting.

3. Final Answer:

   To combine L1 and L2 penalties for better feature selection and stability -> Option C

4. Quick Check:

   Elastic Net = L1 + L2 penalties [OK]

Hint: Elastic Net mixes L1 and L2 to select features and stabilize [OK]

Common Mistakes:

• Thinking Elastic Net only uses L1 or L2 alone
• Believing it increases features instead of selecting
• Confusing Elastic Net with no regularization

2. Which of the following is the correct way to create an Elastic Net model in Python using scikit-learn with both alpha and l1_ratio explicitly specified?

easy

A. from sklearn.linear_model import ElasticNet
model = ElasticNet(alpha=1.0, l1_ratio=0.5)

B. from sklearn.linear_model import ElasticNet
model = ElasticNet(l1_ratio=1.0)

C. from sklearn.linear_model import ElasticNet
model = ElasticNet(alpha=0.5)

D. from sklearn.linear_model import ElasticNet
model = ElasticNet()

Solution

1. Step 1: Check ElasticNet import and parameters

   ElasticNet requires alpha (overall penalty strength) and l1_ratio (balance between L1 and L2).

2. Step 2: Validate correct parameter usage

   from sklearn.linear_model import ElasticNet model = ElasticNet(alpha=1.0, l1_ratio=0.5) correctly sets both alpha and l1_ratio, which are needed for ElasticNet.

3. Final Answer:

   from sklearn.linear_model import ElasticNet model = ElasticNet(alpha=1.0, l1_ratio=0.5) -> Option A

4. Quick Check:

   ElasticNet needs alpha and l1_ratio [OK]

Hint: Always set alpha and l1_ratio when creating ElasticNet [OK]

Common Mistakes:

• Omitting l1_ratio parameter
• Setting only l1_ratio without alpha
• Using ElasticNet without importing

3. Given the following code, what will be the output of print(model.coef_)?

from sklearn.linear_model import ElasticNet
import numpy as np
X = np.array([[1, 2], [3, 4], [5, 6]])
y = np.array([1, 2, 3])
model = ElasticNet(alpha=0.1, l1_ratio=0.7)
model.fit(X, y)
print(model.coef_)

medium

A. [0.4 0.4]

B. [0.5 0.5]

C. [0. 0.]

D. [0. 0.47]

Solution

1. Step 1: Understand ElasticNet fitting

   ElasticNet fits coefficients balancing L1 and L2 penalties; with alpha=0.1 and l1_ratio=0.7, coefficients shrink but remain positive.

2. Step 2: Check typical coefficient values

   Fitting this simple data yields coefficients [0. 0.47] due to L1 sparsity (first coef 0 from OLS) and shrinkage on second.

3. Final Answer:

   [0. 0.47] -> Option D

4. Quick Check:

   ElasticNet coefficients shrink but not zero [OK]

Hint: ElasticNet shrinks coefficients, expect moderate positive values [OK]

Common Mistakes:

• Expecting zero coefficients with small alpha
• Assuming coefficients equal 0.5 without fitting
• Confusing output with no regularization

4. Identify the best practice issue in this Elastic Net usage and how to fix it:

from sklearn.linear_model import ElasticNet
model = ElasticNet(alpha=0.5)
model.fit(X, y)

Assuming X and y are defined.

medium

A. Missing l1_ratio parameter; add l1_ratio between 0 and 1

B. alpha must be zero; set alpha=0

C. ElasticNet does not have fit method; use fit_transform

D. X and y must be lists, not arrays

Solution

1. Step 1: Check ElasticNet parameters

   ElasticNet requires l1_ratio to balance L1 and L2 penalties; default is 0.5 but best to specify explicitly.

2. Step 2: Fix by adding l1_ratio

   Add l1_ratio parameter with a value between 0 and 1 to avoid ambiguity and ensure correct regularization.

3. Final Answer:

   Missing l1_ratio parameter; add l1_ratio between 0 and 1 -> Option A

4. Quick Check:

   ElasticNet needs l1_ratio set [OK]

Hint: Always specify l1_ratio with alpha in ElasticNet [OK]

Common Mistakes:

• Assuming alpha=0.5 is invalid
• Using fit_transform instead of fit
• Thinking X and y must be lists

5. You want to build a model that selects important features but also keeps coefficients stable to avoid overfitting. Which Elastic Net parameters should you adjust and how?

hard

A. Set alpha to zero and l1_ratio to 1 to use only L1 penalty

B. Increase alpha to strengthen regularization and set l1_ratio near 0.5 to balance L1 and L2

C. Decrease alpha and set l1_ratio to zero to use only L2 penalty

D. Set alpha high and l1_ratio to zero to remove all penalties

Solution

1. Step 1: Understand parameter roles

   Alpha controls overall penalty strength; higher alpha means stronger regularization. L1_ratio balances L1 (feature selection) and L2 (stability).

2. Step 2: Choose parameters for feature selection and stability

   Increasing alpha helps reduce overfitting. Setting l1_ratio near 0.5 balances feature selection and coefficient stability.

3. Final Answer:

   Increase alpha to strengthen regularization and set l1_ratio near 0.5 to balance L1 and L2 -> Option B

4. Quick Check:

   Alpha up + l1_ratio ~0.5 = balanced Elastic Net [OK]

Hint: Boost alpha and balance l1_ratio around 0.5 for best results [OK]

Common Mistakes:

• Setting alpha to zero removes regularization
• Using l1_ratio 0 or 1 only applies one penalty
• Confusing penalty effects on overfitting