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ML engineering pipelines

Feature prep, batch inference, model-serving hooks, and production ML workflow glue.

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How to Mock ROC AUC in Python

Compute ROC AUC from scratch in Python using pairwise comparisons between positive and negative score distributions, ideal for testing ML models without sklearn.

machine-learning model-evaluation auc

Python

import random
from math import comb


def mock_roc_auc(scores, labels):
    """Compute mock ROC AUC by simulating a classifier's score distribution."""
    random.seed(42)
    n = len(labels)
    pos_scores = [scores[i] for i in range(n) if labels[i] == 1]
    neg_scores = [scores[i] for i in range(n) if labels[i] == …

12 0 Open

ML engineering pipelines easy

How to Run Batch Predictions with a Mock Model in Python

Build a lightweight mock model class and run predictions across a batch of samples, returning results as a plain Python list.

numpy batch ml

Python

import numpy as np

class MockModel:
    def __init__(self, weights):
        self.weights = np.array(weights)

    def predict(self, X):
        return X @ self.weights

def predict_batch(model, batch):
    """Run predictions for a batch of samples and return results as a list."""
    return model.predict(np.array(ba…

14 0 Open

ML engineering pipelines medium

How to Train a Gradient Boosting Regressor in Python

Build and evaluate a scikit-learn GradientBoostingRegressor on a synthetic dataset, printing test MSE and feature importances.

sklearn gradient-boosting regression

Python

import numpy as np
from sklearn.ensemble import GradientBoostingRegressor
from sklearn.metrics import mean_squared_error

def train_gradient_boosting_mock():
    # Toy regression dataset
    np.random.seed(42)
    X = np.random.rand(100, 3) * 10
    y = 2 * X[:, 0] - 1.5 * X[:, 1] + 0.5 * X[:, 2] + np.random.normal(0,…

13 0 Open

ML engineering pipelines easy

How to do feature selection with VarianceThreshold in Python

This code demonstrates how to use scikit-learn's VarianceThreshold to remove low-variance features from a NumPy array, keeping only those that vary enough to be useful for modeling.

feature selection sklearn machine learning

Python

import numpy as np
from sklearn.feature_selection import VarianceThreshold

def main():
    # Mock dataset: 4 samples, 5 features
    X = np.array([
        [0.1, 0.2, 1.0, 1.0, 0.5],
        [0.2, 0.2, 0.0, 1.0, 0.4],
        [0.1, 0.2, 1.0, 1.0, 0.6],
        [0.3, 0.2, 1.0, 0.0, 0.5]
    ])

    # Select features w…

14 0 Open

ML engineering pipelines medium

K-Fold Cross Validation in Python: A Simple Implementation

Implements k-fold cross validation from scratch, splitting data into folds and computing MSE scores for a baseline mean-predictor model.

cross-validation ml model-evaluation

Python

import random
from statistics import mean


def cross_validation_scores(data, labels, k=5, seed=42):
    random.seed(seed)
    indices = list(range(len(data)))
    random.shuffle(indices)
    fold_size = len(indices) // k
    folds = []
    for i in range(k):
        if i == k - 1:
            folds.append(indices[i *…

16 0 Open

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