docs/usage_examples.md

# Usage Examples

This document provides comprehensive examples for using the English-Shona Language Identification Dataset.

## 🚀 Quick Start with MLOps

### 1. Setup Environment
```bash
# Clone and setup
git clone https://huggingface.co/datasets/omanyasa/english-shona-langid
cd english-shona-langid

# Create reproducible environment
conda env create -f environment.yml
conda activate english-shona-langid
```

### 2. Validate Dataset
```bash
# Run comprehensive tests
pytest tests/test_dataset.py -v

# Quick data quality check
python -c "
from datasets import load_dataset
dataset = load_dataset('omanyasa/english-shona-langid')
print(f'✅ Dataset loaded: {len(dataset[\"train\"])} train samples')
print(f'🌍 Languages: {sorted(set(dataset[\"train\"][\"label\"]))}')
"
```

### 3. Benchmark Baselines
```bash
# Run baseline benchmarks
python scripts/benchmark.py --max-samples 10000

# Results saved as:
# - benchmark_results_*.json
# - confusion_matrix_*.png
```

## Basic Usage

### Loading the Dataset

```python
from datasets import load_dataset

# Load the entire dataset
dataset = load_dataset("omanyasa/english-shona-langid")

# Load specific splits
train_dataset = load_dataset("omanyasa/english-shona-langid", split="train")
validation_dataset = load_dataset("omanyasa/english-shona-langid", split="validation")
test_dataset = load_dataset("omanyasa/english-shona-langid", split="test")

print(f"Train samples: {len(train_dataset)}")
print(f"Validation samples: {len(validation_dataset)}")
print(f"Test samples: {len(test_dataset)}")
```

### Exploring the Data

```python
# View sample data
print("Sample data:")
for i in range(5):
    print(f"Text: {train_dataset[i]['text'][:100]}...")
    print(f"Label: {train_dataset[i]['label']}")
    print("-" * 50)

# Check label distribution
from collections import Counter
label_counts = Counter(train_dataset['label'])
print("Label distribution in training set:")
for label, count in label_counts.items():
    print(f"{label}: {count} samples")
```

## Machine Learning Examples

### 1. Traditional ML Approach (Scikit-learn)

```python
from datasets import load_dataset
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.metrics import classification_report, accuracy_score
import numpy as np

# Load dataset
dataset = load_dataset("omanyasa/english-shona-langid")
train_texts = dataset['train']['text']
train_labels = dataset['train']['label']
test_texts = dataset['test']['text']
test_labels = dataset['test']['label']

# Feature extraction
vectorizer = TfidfVectorizer(max_features=10000, ngram_range=(1, 3))
X_train = vectorizer.fit_transform(train_texts)
X_test = vectorizer.transform(test_texts)

# Train model
model = LogisticRegression(max_iter=1000, random_state=42)
model.fit(X_train, train_labels)

# Evaluate
y_pred = model.predict(X_test)
print(f"Accuracy: {accuracy_score(test_labels, y_pred):.4f}")
print("\nClassification Report:")
print(classification_report(test_labels, y_pred))
```

### 2. Deep Learning with PyTorch

```python
import torch
import torch.nn as nn
from torch.utils.data import DataLoader, Dataset
from datasets import load_dataset
from transformers import AutoTokenizer
import numpy as np

class TextDataset(Dataset):
    def __init__(self, texts, labels, tokenizer, max_length=128):
        self.texts = texts
        self.labels = labels
        self.tokenizer = tokenizer
        self.max_length = max_length
        
        # Create label mapping
        unique_labels = list(set(labels))
        self.label_to_id = {label: idx for idx, label in enumerate(unique_labels)}
        self.id_to_label = {idx: label for label, idx in self.label_to_id.items()}
    
    def __len__(self):
        return len(self.texts)
    
    def __getitem__(self, idx):
        text = self.texts[idx]
        label = self.labels[idx]
        
        encoding = self.tokenizer(
            text,
            truncation=True,
            padding='max_length',
            max_length=self.max_length,
            return_tensors='pt'
        )
        
        return {
            'input_ids': encoding['input_ids'].flatten(),
            'attention_mask': encoding['attention_mask'].flatten(),
            'labels': torch.tensor(self.label_to_id[label], dtype=torch.long)
        }

class LanguageClassifier(nn.Module):
    def __init__(self, vocab_size, embed_dim=128, hidden_dim=256, num_classes=5):
        super().__init__()
        self.embedding = nn.Embedding(vocab_size, embed_dim)
        self.lstm = nn.LSTM(embed_dim, hidden_dim, batch_first=True)
        self.fc = nn.Linear(hidden_dim, num_classes)
        self.dropout = nn.Dropout(0.2)
    
    def forward(self, input_ids, attention_mask):
        embedded = self.embedding(input_ids)
        lstm_out, _ = self.lstm(embedded)
        pooled = lstm_out[:, -1, :]  # Use last hidden state
        output = self.dropout(pooled)
        return self.fc(output)

# Training setup
device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
tokenizer = AutoTokenizer.from_pretrained('bert-base-multilingual-cased')

# Load and prepare data
dataset = load_dataset("omanyasa/english-shona-langid")
train_dataset = TextDataset(
    dataset['train']['text'], 
    dataset['train']['label'], 
    tokenizer
)
test_dataset = TextDataset(
    dataset['test']['text'], 
    dataset['test']['label'], 
    tokenizer
)

train_loader = DataLoader(train_dataset, batch_size=32, shuffle=True)
test_loader = DataLoader(test_dataset, batch_size=32)

# Initialize model
model = LanguageClassifier(
    vocab_size=tokenizer.vocab_size,
    num_classes=len(train_dataset.label_to_id)
).to(device)

optimizer = torch.optim.Adam(model.parameters(), lr=0.001)
criterion = nn.CrossEntropyLoss()

# Training loop
for epoch in range(5):
    model.train()
    total_loss = 0
    
    for batch in train_loader:
        input_ids = batch['input_ids'].to(device)
        attention_mask = batch['attention_mask'].to(device)
        labels = batch['labels'].to(device)
        
        optimizer.zero_grad()
        outputs = model(input_ids, attention_mask)
        loss = criterion(outputs, labels)
        loss.backward()
        optimizer.step()
        
        total_loss += loss.item()
    
    print(f"Epoch {epoch+1}, Loss: {total_loss/len(train_loader):.4f}")
```

### 3. Transformers with Hugging Face

```python
from datasets import load_dataset
from transformers import (
    AutoTokenizer, 
    AutoModelForSequenceClassification,
    TrainingArguments, 
    Trainer
)
import numpy as np
from sklearn.metrics import accuracy_score, f1_score

# Load dataset
dataset = load_dataset("omanyasa/english-shona-langid")

# Create label mappings
labels = dataset['train'].features['label'].names
label2id = {label: i for i, label in enumerate(labels)}
id2label = {i: label for i, label in enumerate(labels)}

# Initialize tokenizer and model
model_name = "distilbert-base-multilingual-cased"
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForSequenceClassification.from_pretrained(
    model_name,
    num_labels=len(labels),
    label2id=label2id,
    id2label=id2label
)

# Preprocessing function
def preprocess_function(examples):
    return tokenizer(
        examples["text"], 
        truncation=True, 
        padding="max_length",
        max_length=128
    )

# Tokenize dataset
tokenized_dataset = dataset.map(
    preprocess_function, 
    batched=True,
    remove_columns=dataset["train"].column_names
)

# Evaluation metrics
def compute_metrics(eval_pred):
    predictions, labels = eval_pred
    predictions = np.argmax(predictions, axis=1)
    
    accuracy = accuracy_score(labels, predictions)
    f1_macro = f1_score(labels, predictions, average='macro')
    f1_weighted = f1_score(labels, predictions, average='weighted')
    
    return {
        'accuracy': accuracy,
        'f1_macro': f1_macro,
        'f1_weighted': f1_weighted
    }

# Training arguments
training_args = TrainingArguments(
    output_dir="./results",
    learning_rate=2e-5,
    per_device_train_batch_size=16,
    per_device_eval_batch_size=16,
    num_train_epochs=3,
    weight_decay=0.01,
    evaluation_strategy="epoch",
    save_strategy="epoch",
    load_best_model_at_end=True,
    metric_for_best_model="f1_macro",
    greater_is_better=True,
)

# Initialize trainer
trainer = Trainer(
    model=model,
    args=training_args,
    train_dataset=tokenized_dataset["train"],
    eval_dataset=tokenized_dataset["validation"],
    compute_metrics=compute_metrics,
)

# Train model
trainer.train()

# Evaluate on test set
test_results = trainer.evaluate(tokenized_dataset["test"])
print("Test Results:", test_results)

# Save model
trainer.save_model("./language_id_model")
tokenizer.save_pretrained("./language_id_model")
```

## Inference Examples

### 1. Using Trained Model for Prediction

```python
from transformers import pipeline
import torch

# Load the trained model
model_path = "./language_id_model"
classifier = pipeline(
    "text-classification",
    model=model_path,
    tokenizer=model_path,
    device=0 if torch.cuda.is_available() else -1
)

# Sample texts for prediction
texts = [
    "Hello, how are you today?",  # English
    "Mhoro, makadii sei?",        # Shona
    "Sawubona, unjani?",          # Ndebele
    "Shani, mwaposa bwanji?",     # Tonga
    "Moni, muli bwanji?"          # Chewa
]

# Make predictions
predictions = classifier(texts)
for text, pred in zip(texts, predictions):
    print(f"Text: {text}")
    print(f"Predicted Language: {pred['label']} (Confidence: {pred['score']:.4f})")
    print("-" * 50)
```

### 2. Real-time Language Detection

```python
import gradio as gr
from transformers import pipeline

# Load model
classifier = pipeline(
    "text-classification",
    model="./language_id_model",
    tokenizer="./language_id_model"
)

def detect_language(text):
    if not text.strip():
        return "Please enter some text..."
    
    result = classifier(text)[0]
    language = result['label']
    confidence = result['score']
    
    return f"Detected Language: {language} (Confidence: {confidence:.2%})"

# Create Gradio interface
iface = gr.Interface(
    fn=detect_language,
    inputs=gr.Textbox(lines=3, placeholder="Enter text to detect language..."),
    outputs="text",
    title="African Language Detector",
    description="Detects English, Shona, Ndebele, Tonga, or Chewa from input text"
)

# Launch interface
iface.launch()
```

## Data Analysis Examples

### 1. Text Length Analysis

```python
from datasets import load_dataset
import matplotlib.pyplot as plt
import seaborn as sns
import pandas as pd

# Load dataset
dataset = load_dataset("omanyasa/english-shona-langid")

# Analyze text lengths by language
def analyze_text_lengths(split_name):
    data = dataset[split_name]
    df = pd.DataFrame({
        'text': data['text'],
        'label': data['label'],
        'length': [len(text.split()) for text in data['text']]
    })
    
    plt.figure(figsize=(12, 6))
    sns.boxplot(data=df, x='label', y='length')
    plt.title(f'Text Length Distribution by Language ({split_name} set)')
    plt.xlabel('Language')
    plt.ylabel('Word Count')
    plt.xticks(rotation=45)
    plt.tight_layout()
    plt.show()
    
    return df.groupby('label')['length'].describe()

# Analyze training set
train_stats = analyze_text_lengths('train')
print("Text Length Statistics:")
print(train_stats)
```

### 2. Vocabulary Analysis

```python
from collections import Counter
import numpy as np

def analyze_vocabulary(split_name):
    data = dataset[split_name]
    
    vocab_by_language = {}
    for label in set(data['label']):
        texts = [text for text, lang in zip(data['text'], data['label']) if lang == label]
        words = ' '.join(texts).lower().split()
        vocab_by_language[label] = Counter(words)
    
    # Print vocabulary statistics
    for language, vocab in vocab_by_language.items():
        print(f"\n{language}:")
        print(f"  Unique words: {len(vocab)}")
        print(f"  Total words: {sum(vocab.values())}")
        print(f"  Top 10 words: {vocab.most_common(10)}")
    
    return vocab_by_language

vocab_stats = analyze_vocabulary('train')
```

## Error Analysis

```python
from sklearn.metrics import confusion_matrix
import seaborn as sns
import matplotlib.pyplot as plt

def analyze_errors(model, test_loader, device):
    model.eval()
    all_preds = []
    all_labels = []
    
    with torch.no_grad():
        for batch in test_loader:
            input_ids = batch['input_ids'].to(device)
            attention_mask = batch['attention_mask'].to(device)
            labels = batch['labels'].to(device)
            
            outputs = model(input_ids, attention_mask)
            preds = torch.argmax(outputs, dim=1)
            
            all_preds.extend(preds.cpu().numpy())
            all_labels.extend(labels.cpu().numpy())
    
    # Confusion matrix
    cm = confusion_matrix(all_labels, all_preds)
    
    plt.figure(figsize=(10, 8))
    sns.heatmap(cm, annot=True, fmt='d', cmap='Blues',
                xticklabels=labels, yticklabels=labels)
    plt.title('Confusion Matrix')
    plt.xlabel('Predicted')
    plt.ylabel('Actual')
    plt.show()
    
    return cm

# Use after training your model
# cm = analyze_errors(model, test_loader, device)
```

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These examples provide a comprehensive guide for using the English-Shona Language Identification Dataset in various scenarios. Feel free to adapt them to your specific needs!