Sign Up


Have an account? Sign In Now

Sign In


Forgot Password?

Don't have account, Sign Up Here

Forgot Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

Have an account? Sign In Now

Sorry, you do not have permission to ask a question, You must login to ask a question.


Forgot Password?

Need An Account, Sign Up Here

Sorry, you do not have permission to add post.


Forgot Password?

Need An Account, Sign Up Here

Please briefly explain why you feel this question should be reported.

Please briefly explain why you feel this answer should be reported.

Please briefly explain why you feel this user should be reported.

Technomantic Logo Technomantic Logo
Sign InSign Up

Technomantic

Search
Ask A Question

Mobile menu

Close
Ask A Question
  • Home
  • Add group
  • Groups page
  • Feed
  • User Profile
  • Communities
  • Questions
    • New Questions
    • Trending Questions
    • Must read Questions
    • Hot Questions
  • Polls
  • Tags
  • Badges
  • Users
  • Help
Home/ Questions/Q 21630
In Process

Technomantic Latest Questions

joseph1
  • 5
  • 5
joseph1Begginer
Asked: May 29, 20252025-05-29T21:46:38+00:00 2025-05-29T21:46:38+00:00In: Artificial Intelligence

What's the best way to normalize data without leaking info from the test set into the training process?

  • 5
  • 5

I used StandardScaler on the entire dataset before splitting, and later realized that might be wrong. How should I handle scaling correctly to avoid leakage?

aiml
2
  • 2 2 Answers
  • 165 Views
  • 0 Followers
  • 0
    • Report
  • Share
    Share
    • Share on Facebook
    • Share on Twitter
    • Share on LinkedIn
    • Share on WhatsApp

You must login to add an answer.


Forgot Password?

Need An Account, Sign Up Here

2 Answers

  • Voted
  • Oldest
  • Recent
  • Random
  1. Charlesg
    Charlesg Begginer
    2025-05-29T22:25:08+00:00Added an answer on May 29, 2025 at 10:25 pm

    When I first started working with machine learning, I made this classic mistake: I normalized my entire dataset before splitting it. And guess what? My model performed great a little too great. 😅
    Turns out, I was leaking information from the test set into training without even realizing it.

    Here’s what I do now (and always recommend):

    1. First, split your data into train and test (or train/val/test).
    2. Fit your scaler only on the training set — not the whole dataset.

      python
      scaler = StandardScaler()
      scaler.fit(X_train)
    3. Then use that same scaler to transform both the training and test sets.

      python
      X_train_scaled = scaler.transform(X_train)
      X_test_scaled = scaler.transform(X_test)

    That way, your model learns only from the training data — just like it would in a real-world setting. No sneak peeks at the test set.
    Trust me, once you catch this, you’ll never scale data the old way again. It’s a small thing, but it makes a huge difference in keeping your model honest.

      • 1
    • Share
      Share
      • Share on Facebook
      • Share on Twitter
      • Share on LinkedIn
      • Share on WhatsApp
      • Report
  2. Hassaan Arif
    Hassaan Arif Enlightened
    2025-05-31T13:25:53+00:00Added an answer on May 31, 2025 at 1:25 pm

    To normalize data without leaking test set information, always follow this golden rule: compute normalization parameters only on the training data.

    Here’s the correct process:

    Split your data first – before any preprocessing.

    Fit the scaler only on training data – e.g.,

    scaler.fit(X_train).

    Transform both sets using that scaler –

    scaler.transform(X_train) and scaler.transform(X_test).

    This ensures your model only learns from what it truly should know, preserving the integrity of your evaluation. It’s a small step with a huge impact think of it as respecting the boundary between practice and the real test.

      • 0
    • Share
      Share
      • Share on Facebook
      • Share on Twitter
      • Share on LinkedIn
      • Share on WhatsApp
      • Report

Sidebar

Ask A Question

Stats

  • Questions 14
  • Answers 19
  • Best Answers 0
  • Users 13
  • Popular
  • Answers
  • joseph1

    What's the best way to normalize data without leaking info ...

    • 2 Answers
  • Charlesg

    Anybody knows good methods to debug autograd issues in dynamic ...

    • 2 Answers
  • Jiyakhan

    What are the most beginner-friendly tools/platforms to prototype a voice ...

    • 2 Answers
  • Rety1
    Rety1 added an answer Ah yes, the imbalanced dataset problem. I’ve come across this… May 31, 2025 at 10:57 pm
  • luke
    luke added an answer From my experience working on chatbot projects, the effectiveness of… May 31, 2025 at 10:41 pm
  • kalim
    kalim added an answer In my machine learning projects, feature selection is a crucial… May 31, 2025 at 10:32 pm

Top Members

Hassaan Arif

Hassaan Arif

  • 0 Questions
  • 5k Points
Enlightened
Rundu

Rundu

  • 2 Questions
  • 35 Points
Begginer
Charlesg

Charlesg

  • 1 Question
  • 31 Points
Begginer

Trending Tags

ai ai lead gen ai tools ai voice agents ai writing deep learning ml nlp object detection

Explore

  • Home
  • Groups page
  • Communities
  • Questions
    • New Questions
    • Trending Questions
    • Must read Questions
    • Hot Questions
  • Polls
  • Tags
  • Help

Footer

Technomantic

Technomantic the AI Platform for asking questions, solve AI problems, and connect on machine learning, ChatGPT, NLP, and prompt engineering topics.

About Us

  • About Us
  • Contact Us
  • Blog
  • Contribute

Legal Stuff

  • Disclaimer
  • Privacy Policy
  • Terms and Conditions
  • Community Guidelines / Forum Rules

Help

  • Contact Us

© 2025 Technomantic. All Rights Reserved