Add empirical comparison study and comprehensive test suite

- Implemented deterministic quicksort (first element as pivot)
- Added comprehensive empirical comparison between randomized and deterministic quicksort
- Expanded test suite from 30+ to 41+ tests covering:
  * Deterministic quicksort tests
  * Algorithm comparison tests
  * Edge case tests
  * Worst-case scenario tests
- Updated README with comparison study documentation
- All 57 tests passing successfully
This commit is contained in:
Carlos Gutierrez
2025-11-04 22:29:10 -05:00
parent a7fe11fd74
commit fc9197dd29
5 changed files with 1062 additions and 3 deletions

101
README.md
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@@ -147,6 +147,16 @@ Hash Table (size=8)
* **Purpose**: Analyze quicksort performance across different array sizes
* **Returns**: List of performance metrics for each array size
##### 5. `deterministic_quicksort(arr)`
* **Purpose**: Sort array using deterministic quicksort (first element as pivot)
* **Parameters**: `arr` (list) - Input array to be sorted
* **Returns**: `list` - New array sorted in ascending order
* **Time Complexity**:
- Average: O(n log n)
- Worst: O(n²) - occurs on sorted/reverse-sorted arrays
* **Note**: Included for empirical comparison with randomized version
#### Algorithm Logic
**Why Randomization?**
@@ -388,6 +398,20 @@ python3 run_tests.py --negative
python3 -m unittest discover tests -v
```
#### Run Empirical Comparison
**Generate Comparison Plots:**
```bash
python3 -m src.generate_plots
```
**Run Comparison Analysis:**
```bash
python3 -m src.quicksort_comparison
```
Both commands will generate detailed performance data and visualizations comparing Randomized vs Deterministic Quicksort.
## Test Cases
### Randomized Quicksort Tests
@@ -415,6 +439,29 @@ The test suite includes comprehensive test cases covering:
* Performance analysis across different array sizes
* Timing measurements
### Deterministic Quicksort Tests
The test suite includes comprehensive test cases covering:
#### ✅ **Functional Tests**
* All same scenarios as randomized quicksort
* Worst-case performance on sorted/reverse-sorted arrays
* Correctness verification
#### ✅ **Comparison Tests**
* Direct comparison between randomized and deterministic quicksort
* Verification that both produce identical results
* Performance consistency tests
#### ✅ **Edge Cases**
* Zero elements, single element, two elements
* All zeros, mixed positive/negative numbers
* Large value ranges
* Worst-case scenarios for deterministic quicksort
### Hash Table Tests
The test suite includes comprehensive test cases covering:
@@ -441,13 +488,41 @@ The test suite includes comprehensive test cases covering:
* All keys hash to same bucket
* Load factor threshold triggering resize
## Empirical Comparison Study
### Randomized vs Deterministic Quicksort
This project includes a comprehensive empirical comparison study comparing Randomized Quicksort with Deterministic Quicksort (using first element as pivot) across different input sizes and distributions.
**Documentation**: See [`QUICKSORT_COMPARISON.md`](QUICKSORT_COMPARISON.md) for detailed analysis and results.
**Visualizations**: Three comprehensive plots are included:
- `quicksort_comparison_plots.png` - Overview comparison across all distributions
- `quicksort_comparison_detailed.png` - Detailed views for each distribution type
- `quicksort_speedup_comparison.png` - Speedup ratios visualization
**Key Findings**:
- **Random Arrays**: Both algorithms perform similarly (~10-15% difference)
- **Sorted Arrays**: Deterministic degrades to O(n²); Randomized maintains O(n log n) - up to **475x speedup**
- **Reverse-Sorted Arrays**: Even worse degradation for deterministic - up to **857x speedup** for randomized
- **Repeated Elements**: Similar performance for both algorithms
**Running the Comparison**:
```bash
# Generate plots and detailed comparison
python3 -m src.generate_plots
python3 -m src.quicksort_comparison
```
## Project Structure
```
MSCS532_Assignment3/
├── src/
│ ├── __init__.py # Package initialization
│ ├── quicksort.py # Randomized Quicksort implementation
│ ├── quicksort.py # Randomized & Deterministic Quicksort implementations
│ ├── quicksort_comparison.py # Empirical comparison script
│ ├── generate_plots.py # Plot generation script
│ ├── hash_table.py # Hash Table with Chaining implementation
│ └── examples.py # Example usage demonstrations
├── tests/
@@ -456,6 +531,10 @@ MSCS532_Assignment3/
│ └── test_hash_table.py # Comprehensive hash table tests
├── run_tests.py # Test runner with various options
├── README.md # This documentation
├── QUICKSORT_COMPARISON.md # Empirical comparison documentation
├── quicksort_comparison_plots.png # Overview comparison plots
├── quicksort_comparison_detailed.png # Detailed distribution plots
├── quicksort_speedup_comparison.png # Speedup ratio plots
├── LICENSE # MIT License
├── .gitignore # Git ignore file
└── requirements.txt # Python dependencies (none required)
@@ -465,7 +544,7 @@ MSCS532_Assignment3/
### Test Coverage
The project includes **30+ comprehensive test cases** covering:
The project includes **41+ comprehensive test cases** covering:
#### ✅ **Functional Tests**
@@ -540,6 +619,24 @@ This implementation serves as an excellent learning resource for:
- Comparable to merge sort but with better space efficiency
- Generally slower than Python's built-in Timsort (optimized hybrid)
### Empirical Comparison Results
**Randomized vs Deterministic Quicksort:**
The project includes comprehensive empirical analysis comparing Randomized Quicksort with Deterministic Quicksort (first element as pivot). Results demonstrate:
1. **On Random Arrays**: Deterministic is ~10-15% faster (minimal overhead from randomization)
2. **On Sorted Arrays**: Randomized is **up to 475x faster** (deterministic shows O(n²) worst-case)
3. **On Reverse-Sorted Arrays**: Randomized is **up to 857x faster** (even worse degradation for deterministic)
4. **On Repeated Elements**: Both perform similarly (~5% difference)
**Visual Evidence**: The included plots (`quicksort_comparison_*.png`) clearly show:
- Exponential degradation curves for deterministic quicksort on worst-case inputs
- Consistent O(n log n) performance for randomized quicksort across all distributions
- Minimal overhead of randomization on random inputs
See [`QUICKSORT_COMPARISON.md`](QUICKSORT_COMPARISON.md) for detailed analysis, tables, and conclusions.
### Hash Table with Chaining
**Chaining vs. Open Addressing:**