diff --git a/json_to_files.py b/json_to_files.py new file mode 100644 index 00000000..e69de29b diff --git a/questions/140_bernoulli-naive-bayes-classifier/description.md b/questions/140_bernoulli-naive-bayes-classifier/description.md new file mode 100644 index 00000000..bcd62b6c --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/description.md @@ -0,0 +1 @@ +Write a Python class to implement the Bernoulli Naive Bayes classifier for binary (0/1) feature data. Your class should have two methods: `forward(self, X, y)` to train on the input data (X: 2D NumPy array of binary features, y: 1D NumPy array of class labels) and `predict(self, X)` to output predicted labels for a 2D test matrix X. Use Laplace smoothing (parameter: smoothing=1.0). Return predictions as a NumPy array. Only use NumPy. Predictions must be binary (0 or 1) and you must handle cases where the training data contains only one class. All log/likelihood calculations should use log probabilities for numerical stability. diff --git a/questions/140_bernoulli-naive-bayes-classifier/example.json b/questions/140_bernoulli-naive-bayes-classifier/example.json new file mode 100644 index 00000000..fc8cc328 --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/example.json @@ -0,0 +1,5 @@ +{ + "input": "X = np.array([[1, 0, 1], [1, 1, 0], [0, 0, 1], [0, 1, 0], [1, 1, 1]]); y = np.array([1, 1, 0, 0, 1])\nmodel = NaiveBayes(smoothing=1.0)\nmodel.forward(X, y)\nprint(model.predict(np.array([[1, 0, 1]])))", + "output": "[1]", + "reasoning": "The model learns class priors and feature probabilities with Laplace smoothing. For [1, 0, 1], the posterior for class 1 is higher, so the model predicts 1." +} diff --git a/questions/140_bernoulli-naive-bayes-classifier/learn.md b/questions/140_bernoulli-naive-bayes-classifier/learn.md new file mode 100644 index 00000000..f6e05ccc --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/learn.md @@ -0,0 +1,51 @@ +# **Naive Bayes Classifier** + +## **1. Definition** + +Naive Bayes is a **probabilistic machine learning algorithm** used for **classification tasks**. It is based on **Bayes' Theorem**, which describes the probability of an event based on prior knowledge of related events. + +The algorithm assumes that: +- **Features are conditionally independent** given the class label (the "naive" assumption). +- It calculates the posterior probability for each class and assigns the class with the **highest posterior** to the sample. + +--- + +## **2. Bayes' Theorem** + +Bayes' Theorem is given by: + +$$ +P(C | X) = \frac{P(X | C) \times P(C)}{P(X)} +$$ + +Where: +- $P(C | X)$ **Posterior** probability: the probability of class $C $ given the feature vector $X$ +- $P(X | C)$ → **Likelihood**: the probability of the data $X$ given the class +- $P(C)$ → **Prior** probability: the initial probability of class $C$ before observing any data +- $ P(X)$ → **Evidence**: the total probability of the data across all classes (acts as a normalizing constant) + +Since $P(X)$ is the same for all classes during comparison, it can be ignored, simplifying the formula to: + +$$ +P(C | X) \propto P(X | C) \times P(C) +$$ +--- + +### 3 **Bernoulli Naive Bayes** +- Used for **binary data** (features take only 0 or 1 values). +- The likelihood is given by: + +$$ +P(X | C) = \prod_{i=1}^{n} P(x_i | C)^{x_i} \cdot (1 - P(x_i | C))^{1 - x_i} +$$ + +--- + +## **4. Applications of Naive Bayes** + +- **Text Classification:** Spam detection, sentiment analysis, and news categorization. +- **Document Categorization:** Sorting documents by topic. +- **Fraud Detection:** Identifying fraudulent transactions or behaviors. +- **Recommender Systems:** Classifying users into preference groups. + +--- diff --git a/questions/140_bernoulli-naive-bayes-classifier/meta.json b/questions/140_bernoulli-naive-bayes-classifier/meta.json new file mode 100644 index 00000000..2a87586d --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/meta.json @@ -0,0 +1,15 @@ +{ + "id": "140", + "title": "Bernoulli Naive Bayes Classifier", + "difficulty": "medium", + "category": "Machine Learning", + "video": "", + "likes": "0", + "dislikes": "0", + "contributor": [ + { + "profile_link": "https://github.com/Coder1010ayush", + "name": "Coder1010ayush" + } + ] +} diff --git a/questions/140_bernoulli-naive-bayes-classifier/solution.py b/questions/140_bernoulli-naive-bayes-classifier/solution.py new file mode 100644 index 00000000..2c99379d --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/solution.py @@ -0,0 +1,30 @@ +import numpy as np + +class NaiveBayes(): + def __init__(self, smoothing=1.0): + self.smoothing = smoothing + self.classes = None + self.priors = None + self.likelihoods = None + + def forward(self, X, y): + self.classes, class_counts = np.unique(y, return_counts=True) + self.priors = {cls: np.log(class_counts[i] / len(y)) for i, cls in enumerate(self.classes)} + self.likelihoods = {} + for cls in self.classes: + X_cls = X[y == cls] + prob = (np.sum(X_cls, axis=0) + self.smoothing) / (X_cls.shape[0] + 2 * self.smoothing) + self.likelihoods[cls] = (np.log(prob), np.log(1 - prob)) + + def _compute_posterior(self, sample): + posteriors = {} + for cls in self.classes: + posterior = self.priors[cls] + prob_1, prob_0 = self.likelihoods[cls] + likelihood = np.sum(sample * prob_1 + (1 - sample) * prob_0) + posterior += likelihood + posteriors[cls] = posterior + return max(posteriors, key=posteriors.get) + + def predict(self, X): + return np.array([self._compute_posterior(sample) for sample in X]) diff --git a/questions/140_bernoulli-naive-bayes-classifier/starter_code.py b/questions/140_bernoulli-naive-bayes-classifier/starter_code.py new file mode 100644 index 00000000..09c9820e --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/starter_code.py @@ -0,0 +1,14 @@ +import numpy as np + +class NaiveBayes(): + def __init__(self, smoothing=1.0): + # Initialize smoothing + pass + + def forward(self, X, y): + # Fit model to binary features X and labels y + pass + + def predict(self, X): + # Predict class labels for test set X + pass diff --git a/questions/140_bernoulli-naive-bayes-classifier/tests.json b/questions/140_bernoulli-naive-bayes-classifier/tests.json new file mode 100644 index 00000000..e74c2f58 --- /dev/null +++ b/questions/140_bernoulli-naive-bayes-classifier/tests.json @@ -0,0 +1,22 @@ +[ + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.array([[1, 0, 1], [1, 1, 0], [0, 0, 1], [0, 1, 0], [1, 1, 1]])\ny = np.array([1, 1, 0, 0, 1])\nmodel.forward(X, y)\nprint(model.predict(np.array([[1, 0, 1]])))", + "expected_output": "[1]" + }, + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.array([[0], [1], [0], [1]])\ny = np.array([0, 1, 0, 1])\nmodel.forward(X, y)\nprint(model.predict(np.array([[0], [1]])))", + "expected_output": "[0 1]" + }, + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.array([[0, 0], [1, 0], [0, 1]])\ny = np.array([0, 1, 0])\nmodel.forward(X, y)\nprint(model.predict(np.array([[1, 1]])))", + "expected_output": "[0]" + }, + { + "test": "import numpy as np\nnp.random.seed(42)\nmodel = NaiveBayes(smoothing=1.0)\nX = np.random.randint(0, 2, (100, 5))\ny = np.random.choice([0, 1], size=100)\nmodel.forward(X, y)\nX_test = np.random.randint(0, 2, (10, 5))\npred = model.predict(X_test)\nprint(pred.shape)", + "expected_output": "(10,)" + }, + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.random.randint(0, 2, (10, 3))\ny = np.zeros(10)\nmodel.forward(X, y)\nX_test = np.random.randint(0, 2, (3, 3))\nprint(model.predict(X_test))", + "expected_output": "[0, 0, 0]" + } +] diff --git a/utils/convert_single_question.py b/utils/convert_single_question.py new file mode 100644 index 00000000..ef9f9fae --- /dev/null +++ b/utils/convert_single_question.py @@ -0,0 +1,209 @@ +#!/usr/bin/env python +""" +convert_single_question.py +────────────────────────── +Paste ONE question dict into QUESTION_DICT and run: + + python utils/convert_single_question.py + +The script splits it into: + +questions/_/ + ├─ meta.json + ├─ description.md + ├─ learn.md + ├─ starter_code.py + ├─ solution.py + ├─ example.json + ├─ tests.json + ├─ tinygrad/ (optional) + └─ pytorch/ (optional) +""" + +import base64 +import json +import pathlib +import re +from typing import Any, Dict + +# ── 1️⃣ EDIT YOUR QUESTION HERE ──────────────────────────────────────────── +QUESTION_DICT: Dict[str, Any] = { + 'id':'140', + "description": "Write a Python class to implement the Bernoulli Naive Bayes classifier for binary (0/1) feature data. Your class should have two methods: `forward(self, X, y)` to train on the input data (X: 2D NumPy array of binary features, y: 1D NumPy array of class labels) and `predict(self, X)` to output predicted labels for a 2D test matrix X. Use Laplace smoothing (parameter: smoothing=1.0). Return predictions as a NumPy array. Only use NumPy. Predictions must be binary (0 or 1) and you must handle cases where the training data contains only one class. All log/likelihood calculations should use log probabilities for numerical stability.", + "test_cases": [ + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.array([[1, 0, 1], [1, 1, 0], [0, 0, 1], [0, 1, 0], [1, 1, 1]])\ny = np.array([1, 1, 0, 0, 1])\nmodel.forward(X, y)\nprint(model.predict(np.array([[1, 0, 1]])))", + "expected_output": "[1]" + }, + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.array([[0], [1], [0], [1]])\ny = np.array([0, 1, 0, 1])\nmodel.forward(X, y)\nprint(model.predict(np.array([[0], [1]])))", + "expected_output": "[0 1]" + }, + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.array([[0, 0], [1, 0], [0, 1]])\ny = np.array([0, 1, 0])\nmodel.forward(X, y)\nprint(model.predict(np.array([[1, 1]])))", + "expected_output": "[0]" + }, + { + "test": "import numpy as np\nnp.random.seed(42)\nmodel = NaiveBayes(smoothing=1.0)\nX = np.random.randint(0, 2, (100, 5))\ny = np.random.choice([0, 1], size=100)\nmodel.forward(X, y)\nX_test = np.random.randint(0, 2, (10, 5))\npred = model.predict(X_test)\nprint(pred.shape)", + "expected_output": "(10,)" + }, + { + "test": "import numpy as np\nmodel = NaiveBayes(smoothing=1.0)\nX = np.random.randint(0, 2, (10, 3))\ny = np.zeros(10)\nmodel.forward(X, y)\nX_test = np.random.randint(0, 2, (3, 3))\nprint(model.predict(X_test))", + "expected_output": "[0, 0, 0]" + } + ], + "solution": "import numpy as np\n\nclass NaiveBayes():\n def __init__(self, smoothing=1.0):\n self.smoothing = smoothing\n self.classes = None\n self.priors = None\n self.likelihoods = None\n\n def forward(self, X, y):\n self.classes, class_counts = np.unique(y, return_counts=True)\n self.priors = {cls: np.log(class_counts[i] / len(y)) for i, cls in enumerate(self.classes)}\n self.likelihoods = {}\n for cls in self.classes:\n X_cls = X[y == cls]\n prob = (np.sum(X_cls, axis=0) + self.smoothing) / (X_cls.shape[0] + 2 * self.smoothing)\n self.likelihoods[cls] = (np.log(prob), np.log(1 - prob))\n\n def _compute_posterior(self, sample):\n posteriors = {}\n for cls in self.classes:\n posterior = self.priors[cls]\n prob_1, prob_0 = self.likelihoods[cls]\n likelihood = np.sum(sample * prob_1 + (1 - sample) * prob_0)\n posterior += likelihood\n posteriors[cls] = posterior\n return max(posteriors, key=posteriors.get)\n\n def predict(self, X):\n return np.array([self._compute_posterior(sample) for sample in X])", + "example": { + "input": "X = np.array([[1, 0, 1], [1, 1, 0], [0, 0, 1], [0, 1, 0], [1, 1, 1]]); y = np.array([1, 1, 0, 0, 1])\nmodel = NaiveBayes(smoothing=1.0)\nmodel.forward(X, y)\nprint(model.predict(np.array([[1, 0, 1]])))", + "output": "[1]", + "reasoning": "The model learns class priors and feature probabilities with Laplace smoothing. For [1, 0, 1], the posterior for class 1 is higher, so the model predicts 1." + }, + "category": "Machine Learning", + "starter_code": "import numpy as np\n\nclass NaiveBayes():\n def __init__(self, smoothing=1.0):\n # Initialize smoothing\n pass\n\n def forward(self, X, y):\n # Fit model to binary features X and labels y\n pass\n\n def predict(self, X):\n # Predict class labels for test set X\n pass", + "title": "Bernoulli Naive Bayes Classifier", + "learn_section":r"""# **Naive Bayes Classifier** + +## **1. Definition** + +Naive Bayes is a **probabilistic machine learning algorithm** used for **classification tasks**. It is based on **Bayes' Theorem**, which describes the probability of an event based on prior knowledge of related events. + +The algorithm assumes that: +- **Features are conditionally independent** given the class label (the "naive" assumption). +- It calculates the posterior probability for each class and assigns the class with the **highest posterior** to the sample. + +--- + +## **2. Bayes' Theorem** + +Bayes' Theorem is given by: + +$$ +P(C | X) = \frac{P(X | C) \times P(C)}{P(X)} +$$ + +Where: +- $P(C | X)$ **Posterior** probability: the probability of class $C $ given the feature vector $X$ +- $P(X | C)$ → **Likelihood**: the probability of the data $X$ given the class +- $P(C)$ → **Prior** probability: the initial probability of class $C$ before observing any data +- $ P(X)$ → **Evidence**: the total probability of the data across all classes (acts as a normalizing constant) + +Since $P(X)$ is the same for all classes during comparison, it can be ignored, simplifying the formula to: + +$$ +P(C | X) \propto P(X | C) \times P(C) +$$ +--- + +### 3 **Bernoulli Naive Bayes** +- Used for **binary data** (features take only 0 or 1 values). +- The likelihood is given by: + +$$ +P(X | C) = \prod_{i=1}^{n} P(x_i | C)^{x_i} \cdot (1 - P(x_i | C))^{1 - x_i} +$$ + +--- + +## **4. Applications of Naive Bayes** + +- **Text Classification:** Spam detection, sentiment analysis, and news categorization. +- **Document Categorization:** Sorting documents by topic. +- **Fraud Detection:** Identifying fraudulent transactions or behaviors. +- **Recommender Systems:** Classifying users into preference groups. + +--- """, + "contributor": [ + { + "profile_link": "https://github.com/moe18", + "name": "Moe Chabot" + } + ], + "likes": "0", + "dislikes": "0", + "difficulty": "medium", + "video":'' +} + +# ──────────────────────────────────────────────────────────────────────────── + + +# ---------- helpers --------------------------------------------------------- +def slugify(text: str) -> str: + text = re.sub(r"[^0-9A-Za-z]+", "-", text.lower()) + return re.sub(r"-{2,}", "-", text).strip("-")[:50] + + +def maybe_b64(s: str) -> str: + try: + if len(s) % 4 == 0 and re.fullmatch(r"[0-9A-Za-z+/=\n\r]+", s): + return base64.b64decode(s).decode("utf-8") + except Exception: + pass + return s + + +def write_text(path: pathlib.Path, content: str) -> None: + path.parent.mkdir(parents=True, exist_ok=True) + path.write_text(content.rstrip("\n") + "\n", encoding="utf-8") + + +def write_json(path: pathlib.Path, obj: Any) -> None: + write_text(path, json.dumps(obj, indent=2, ensure_ascii=False)) + + +# ---------- converter ------------------------------------------------------- +def convert_one(q: Dict[str, Any]) -> None: + folder = pathlib.Path("questions") / f"{q['id']}_{slugify(q['title'])}" + folder.mkdir(parents=True, exist_ok=True) + + # meta.json + meta = { + "id": q["id"], + "title": q["title"], + "difficulty": q["difficulty"], + "category": q["category"], + "video": q.get("video", ""), + "likes": q.get("likes", "0"), + "dislikes": q.get("dislikes", "0"), + "contributor": q.get("contributor", []), + } + for opt in ("tinygrad_difficulty", "pytorch_difficulty", "marimo_link"): + if opt in q: + meta[opt] = q[opt] + write_json(folder / "meta.json", meta) + + # core files + write_text(folder / "description.md", q["description"]) + write_text(folder / "learn.md", q["learn_section"]) + write_text(folder / "starter_code.py", q["starter_code"]) + write_text(folder / "solution.py", q["solution"]) + write_json(folder / "example.json", q["example"]) + write_json(folder / "tests.json", q["test_cases"]) + + # optional language-specific extras + for lang in ("tinygrad", "pytorch"): + sc, so, tc = (f"{lang}_starter_code", f"{lang}_solution", f"{lang}_test_cases") + if any(k in q for k in (sc, so, tc)): + sub = folder / lang + if sc in q: + write_text(sub / "starter_code.py", maybe_b64(q[sc])) + if so in q: + write_text(sub / "solution.py", maybe_b64(q[so])) + if tc in q: + write_json(sub / "tests.json", q[tc]) + + # success message (relative if possible) + try: + rel = folder.relative_to(pathlib.Path.cwd()) + except ValueError: + rel = folder + print(f"✓ Created {rel}") + + +# ---------- main ------------------------------------------------------------ +def main() -> None: + convert_one(QUESTION_DICT) + + +if __name__ == "__main__": + main()