Update pages/1KNN Alogrithm.py

pages/1KNN Alogrithm.py

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+import streamlit as st
+
+# Page configuration
+st.set_page_config(page_title="KNN Overview", page_icon="📊", layout="wide")
+
+# Custom CSS styling for a cleaner, light-colored interface
+st.markdown("""
+    <style>
+        .stApp {
+            background-color: #f2f6fa;
+        }
+        h1, h2, h3 {
+            color: #1a237e;
+        }
+        .custom-font, p {
+            font-family: 'Arial', sans-serif;
+            font-size: 18px;
+            color: #212121;
+            line-height: 1.6;
+        }
+    </style>
+""", unsafe_allow_html=True)
+
+# Title
+st.markdown("<h1 style='color: #1a237e;'>Understanding K-Nearest Neighbors (KNN)</h1>", unsafe_allow_html=True)
+
+# Introduction to KNN
+st.write("""
+K-Nearest Neighbors (KNN) is a fundamental machine learning method suitable for both **classification** and **regression** problems. It makes predictions by analyzing the `K` closest data points in the training set.
+
+Key features:
+- KNN is a non-parametric model.
+- It memorizes training data instead of learning a model.
+- Distance metrics like **Euclidean** help determine similarity between data points.
+""")
+
+# How KNN Works
+st.markdown("<h2 style='color: #1a237e;'>How KNN Functions</h2>", unsafe_allow_html=True)
+
+st.subheader("Training Phase")
+st.write("""
+- KNN doesn't train a model in the traditional sense.
+- It stores the dataset and uses it during prediction.
+""")
+
+st.subheader("Prediction - Classification")
+st.write("""
+1. Set the value of `k`.
+2. Calculate the distance between the input and each point in the training data.
+3. Identify the `k` nearest neighbors.
+4. Use majority voting to assign the class label.
+""")
+
+st.subheader("Prediction - Regression")
+st.write("""
+1. Choose `k`.
+2. Find the distances to all training points.
+3. Pick the closest `k` neighbors.
+4. Predict using the **average** or **weighted average** of their values.
+""")
+
+# Overfitting and Underfitting
+st.subheader("Model Behavior")
+st.write("""
+- **Overfitting**: Occurs when the model captures noise by using very low values of `k`.
+- **Underfitting**: Happens when the model oversimplifies, often with high `k` values.
+- **Optimal Fit**: Found by balancing both, often using cross-validation.
+""")
+
+# Training vs CV Error
+st.subheader("Error Analysis")
+st.write("""
+- **Training Error**: Error on the dataset used for fitting.
+- **Cross-Validation Error**: Error on separate validation data.
+- Ideal models show low error in both.
+""")
+
+# Hyperparameter Tuning
+st.subheader("Hyperparameter Choices")
+st.write("""
+Important tuning options for KNN include:
+- `k`: Number of neighbors
+- `weights`: `uniform` or `distance`
+- `metric`: Distance formula like Euclidean or Manhattan
+- `n_jobs`: Parallel processing support
+""")
+
+# Scaling
+st.subheader("Why Scaling is Crucial")
+st.write("""
+KNN relies heavily on distances, so it's essential to scale features. Use:
+- **Min-Max Normalization** to compress values between 0 and 1.
+- **Z-score Standardization** to center data.
+
+Always scale training and testing data separately.
+""")
+
+# Weighted KNN
+st.subheader("Weighted KNN")
+st.write("""
+In Weighted KNN, closer neighbors have more influence on the result. It improves accuracy, especially in noisy or uneven data.
+""")
+
+# Decision Regions
+st.subheader("Decision Boundaries")
+st.write("""
+KNN creates boundaries based on training data:
+- Small `k` = complex, sensitive regions (risk of overfitting).
+- Large `k` = smoother regions (risk of underfitting).
+""")
+
+# Cross Validation
+st.subheader("Cross-Validation")
+st.write("""
+Cross-validation helps evaluate models effectively. For example:
+- **K-Fold CV** divides data into parts and tests each part.
+- Ensures model generalization.
+""")
+
+# Hyperparameter Optimization Techniques
+st.subheader("Tuning Methods")
+st.write("""
+- **Grid Search**: Tests all combinations of parameters.
+- **Random Search**: Picks random combinations for faster tuning.
+- **Bayesian Search**: Uses previous results to make better guesses on parameter selection.
+""")
+
+# Notebook Link
+st.markdown("<h2 style='color: #1a237e;'>KNN Implementation Notebook</h2>", unsafe_allow_html=True)
+st.markdown(
+    "<a href='https://colab.research.google.com/drive/11wk6wt7sZImXhTqzYrre3ic4oj3KFC4M?usp=sharing' target='_blank' style='font-size: 16px; color: #1a237e;'>Click here to open the Colab notebook</a>",
+    unsafe_allow_html=True
+)
+
+st.write("""
+KNN is intuitive and effective when combined with proper preprocessing and hyperparameter tuning. Use cross-validation to find the sweet spot and avoid overfitting or underfitting.
+""")