Implement logistic regression from scratch

Last updated: October 9, 2025

Quick Overview

Write a clean implementation of k-means without using ML libraries.

Elastic
Machine Learning
Machine Learning Engineer
Elastic
October 9, 2025
Machine Learning Engineer
Phone Screen
Machine Learning
Easy

75

6

435 solved


Write a clean implementation of k-means without using ML libraries.

Machine learning questions at Elastic test both theoretical understanding and practical experience. This Phone Screen question evaluates your knowledge of ML fundamentals and your ability to apply them to real-world problems.

What the Interviewer Expects
  • Explain the concept clearly with intuitive examples
  • Discuss when and why to use this technique
  • Identify common pitfalls and how to avoid them
  • Compare with alternative approaches at a high level
Key Topics to Cover
Supervised vs unsupervised learning
Class imbalance handling
Feature importance and selection
Cross-validation and model evaluation
Model interpretability and explainability
How to Approach This
  1. Understand the bias-variance trade-off. High training accuracy but low test accuracy signals overfitting.
  2. Choose evaluation metrics carefully based on the problem. Accuracy alone is often insufficient.
  3. Feature engineering is often more impactful than model selection.
  4. Know when to use tree-based models (tabular data) vs neural networks (unstructured data).
  5. Handle class imbalance with SMOTE, class weights, or appropriate loss functions.
Possible Follow-up Questions
  • What regularization technique would you use and why?
  • How would you ensure reproducibility in your ML pipeline?
  • When would you prefer a simpler model over a complex one?
  • How would you handle a highly imbalanced dataset?
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Explore ML Interview Prep
Sample Answer
Core Concept: K-Means Clustering

K-Means is an unsupervised learning algorithm used for clustering data into distinct groups based on feature similarity. The core idea is to partition the dataset into K clusters, where each data poin...

How It Works: Algorithmic Mechanism

The K-Means algorithm follows these steps:

  1. Initialization: Randomly select K initial centroids from the dataset.
  2. Assignment Step: Assign each data point to the nearest centroid based on ...

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