Merge pull request python-geeks#324 from abhinand5/main

Added Simple Plagiarism Checker

Author: pawangeek

simple_plagiarism_detector/README.md

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+# Simple Plagiarism Checker
+
+This is the simplest way to calculate similarity between two texts. Using cosine similarity between them. So, it is rather a similarity measure between two texts. Which in this case might be useful when comparing two texts for similarity/plagiarism. 
+
+## Requirements 
+Only uses in-built Python packages.
+
+## Usage 
+
+Specify the text files you want to compare while running the script as arguments.
+
+`$ python simple-plagiarism-detector.py file1.txt file2.txt`
+
+**Sample Output:**
+
+`file1.txt` contents
+> This is an example sentence
+
+`file2.txt` contents
+> This sentence is similar to an example sentence
+
+
+`$ python simple-plagiarism-detector.py file1.txt file2.txt`
+
+Similarity Score: 0.8485281374238569
+
+**Contributor:** [abhinand5](https://github.com/abhinand5)

simple_plagiarism_detector/file1.txt

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+:) :(

simple_plagiarism_detector/file2.txt

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+:( :)

simple_plagiarism_detector/simple-plagiarism-detector.py

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+# Simple plagiarism detector
+# Note: This is a very simple example, might not work perfectly
+# Author: Abhinand
+
+import math
+import re
+from collections import Counter
+import sys
+
+WORD = re.compile(r"[A-Za-z0-9]")
+SPECIAL_CHARS = re.compile(r"[^A-Za-z0-9]")
+
+
+def get_cosine(vec1, vec2):
+    """ Function to compute Cosine Similarity between two word vectors"""
+    intersection = set(vec1.keys()) & set(vec2.keys())
+    numerator = sum([vec1[x] * vec2[x] for x in intersection])
+
+    sum1 = sum([vec1[x] ** 2 for x in list(vec1.keys())])
+    sum2 = sum([vec2[x] ** 2 for x in list(vec2.keys())])
+    denominator = math.sqrt(sum1) * math.sqrt(sum2)
+
+    if not denominator:
+        return 0.0
+    else:
+        return float(numerator) / denominator
+
+
+def text_to_vector(text):
+    """Simple function to convert text to vector"""
+    words = WORD.findall(text)
+    special = SPECIAL_CHARS.findall(text)
+    return Counter(words) + Counter(special)
+
+
+if __name__ == "__main__":
+
+    file1 = open(sys.argv[1], "r")
+    text1 = file1.read().replace("\n", " ")
+
+    file2 = open(sys.argv[2], "r")
+    text2 = file2.read().replace("\n", " ")
+
+    if len(text1) == 0 and len(text2) == 0:
+        print("given text files were empty, imputing '1' as place holder")
+        text1 = '' + '1'
+        text2 = '' + '1'
+
+    vector1 = text_to_vector(text1)
+    vector2 = text_to_vector(text2)
+
+    cosine = round(get_cosine(vector1, vector2), 2)
+
+    print("Similarity Score:", cosine)