String Comparison Tool

A Python application for comparing pairs of strings using three metrics:

• Hamming Distance
• Jaccard Similarity
• T Similarity (Tanimoto with character frequencies)

The project applies Object-Oriented Programming (OOP) concepts such as abstraction, inheritance, polymorphism, and separation of responsibilities.

Project Structure

string-comparison-tool/
├── data/
│   ├── raw/
│   │   └── input.csv
│   └── processed/
│       └── output.csv
├── src/
│   ├── base.py
│   ├── control_flow.py
│   ├── hamming.py
│   ├── input_output.py
│   ├── jaccard.py
│   └── tanimoto.py
├── main.py
├── requirements.txt
└── README.md

Requirements

• Python 3
• pandas

Installation

Go to the project directory:

cd string-comparison-tool

Create a virtual environment:

python3 -m venv .venv

Activate it:

source .venv/bin/activate

Install the dependencies:

pip install -r requirements.txt

Input File

The program reads:

data/raw/input.csv

The CSV file must contain:

input_one,input_two

Each row contains two strings to compare.

How to Run

Activate the virtual environment:

source .venv/bin/activate

Create the output directory if necessary:

mkdir -p data/processed

Run the program from the project root:

python main.py

The generated output is saved to:

data/processed/output.csv

Processing Flow

input.csv
    |
    v
extract_data()
    |
    v
control_flow.run()
    |
    +----> Hamming
    |
    +----> Jaccard
    |
    +----> T Similarity
    |
    v
results
    |
    v
write_output()
    |
    v
output.csv

Output

The output CSV contains:

input_one,input_two,H,J,T

Where:

• H = Hamming Distance
• J = Jaccard Similarity
• T = T Similarity

Example:

input_one,input_two,H,J,T
hello,hello,0.0,1.0,1.0
hello,hullo,1.0,0.6,0.6666666666666666

For Hamming Distance, strings with different lengths return an empty value because the algorithm requires strings of equal length.

Class Diagram

                    +------------------------+
                    |    SimilarityMetric    |
                    |         <<ABC>>        |
                    +------------------------+
                    | + calculate(s1, s2)    |
                    +-----------+------------+
                                |
              +-----------------+-----------------+
              |                 |                 |
              v                 v                 v
     +----------------+ +----------------+ +----------------+
     | HammingDistance| |JaccardSimilarity| |  TSimilarity  |
     +----------------+ +----------------+ +----------------+
     | + calculate()  | | + calculate()  | | + calculate()  |
     +----------------+ +----------------+ +----------------+

                    +----------------+
                    |  control_flow  |
                    +----------------+
                    | + run()        |
                    +-------+--------+
                            |
             +--------------+--------------+
             |              |              |
             v              v              v
          Hamming        Jaccard       TSimilarity
                            |
                            v
                    +----------------+
                    | input_output   |
                    +----------------+
                    | + extract_data()|
                    | + write_output()|
                    +----------------+

Class Responsibilities

SimilarityMetric

Defines the common interface for all similarity algorithms through the abstract calculate() method.

HammingDistance

Counts the positions that differ between two strings. Both strings must have the same length.

JaccardSimilarity

Compares the sets of characters in two strings using intersection and union.

TSimilarity

Compares character frequencies using the sum of minimum frequencies divided by the sum of maximum frequencies.

input_output.py

Reads the input CSV with Pandas and writes the calculated results to the output CSV.

control_flow.py

Coordinates the complete process: extraction, metric calculation, and output generation.

main.py

The entry point of the application. It starts the process by calling run().

Technologies

• Python
• Pandas
• Object-Oriented Programming
• Abstract Base Classes
• CSV processing