118 lines
2.8 KiB
Markdown
118 lines
2.8 KiB
Markdown
# fuzzy-match
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A fast command-line tool for fuzzy string matching using the Damerau-Levenshtein distance algorithm, with a longest-common-substring fallback when no strong match is found.
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## Features
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- **Damerau-Levenshtein Distance**: Measures similarity between strings accounting for insertions, deletions, substitutions, and transpositions
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- **Normalized Scoring**: Calculates similarity score as `1 - distance / MAX(queryLength, lineLength)` so higher scores are better
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- **Fallback Matching**: If the best Damerau-Levenshtein similarity is below `0.5`, recalculates every score using the maximal common substring length
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- **Sorted Output**: Results are sorted by similarity score (best matches first)
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- **Efficient Processing**: Handles large input streams with dynamic memory allocation
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## Building
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### Prerequisites
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- GCC compiler
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- Make (optional)
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### Compilation
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Using Make:
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```bash
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make
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```
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Or directly with GCC:
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```bash
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gcc -o fuzzy-match fuzzy-match.c -lm
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```
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## Usage
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```bash
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fuzzy-match <query> < input.txt
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```
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or pipe input from another command:
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```bash
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echo -e "apple\napple pie\norange\nbanana\nappl" | fuzzy-match "apple"
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```
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### Output Format
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Each line is printed with its similarity score (higher is more similar):
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```
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1.0000 apple
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0.8000 appl
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0.5556 apple pie
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0.1667 banana
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0.1667 orange
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```
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## Examples
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### Basic matching
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```bash
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$ echo -e "cat\ncar\ndog\nhat" | fuzzy-match "cat"
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1.0000 cat
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0.6667 car
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0.6667 hat
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0.0000 dog
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```
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### Matching with typos
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```bash
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$ echo -e "programming\nprograming\nprogram\nprogamming" | fuzzy-match "programming"
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1.0000 programming
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0.9091 programing
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0.9091 progamming
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0.6364 program
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```
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### Fallback to maximal common substring
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If no Damerau-Levenshtein similarity reaches `0.5`, every score is recalculated using the longest common substring length instead.
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## Algorithm
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The program first computes a **Damerau-Levenshtein similarity**, based on the minimum number of single-character edits (insertions, deletions, substitutions, and transpositions) needed to transform one string into another.
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The primary similarity score is normalized to account for string length differences:
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```
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similarity_score = 1 - damerau_levenshtein_distance / MAX(query_length, line_length)
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```
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If the highest primary similarity is below `0.5`, the program recalculates every score using the maximal common substring length instead:
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```
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similarity_score = longest_common_substring_length / MAX(query_length, line_length)
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```
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## Installation
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Install to system PATH:
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```bash
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make install
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```
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Uninstall:
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```bash
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make uninstall
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```
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## Cleaning
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Remove compiled binaries:
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```bash
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make clean
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```
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## License
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This project is licensed under the GNU General Public License, version 3.
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See `LICENSE` for the full text.
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