TF-IDF based search for ZK init

bin/zksim

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+#!/usr/bin/env python3
+import sys
+import argparse
+import os
+import sqlite3
+
+try:
+    from sklearn.metrics.pairwise import linear_kernel
+    from sklearn.feature_extraction.text import TfidfVectorizer
+    import pandas as pd
+except ImportError as e:
+    print(f"Missing {e.name}! Please run pip3 install scikit-learn pandas")
+    exit()
+
+
+"""
+This script takes a zettelkasten note filename and sorts the available notes by their similarity
+using Term Frequency-Inverse Document Frequency (TF-IDF). The idea is to use this to help one make
+connections in their zettelkasten they may have not thought of initially. 
+
+I'm not sure how well this works in practice yet since my zettelkasten is just starting to fill up.
+It does seem to find notes I would say are generally related. I have limited the search to print the
+top 20 matches.
+
+I currently utilize sirupsen's search tool to use this (https://github.com/sirupsen/zk/blob/master/bin/zks). 
+I have a second search function for when I want to try TF-IDF that puts 'python --filename "zk filename.md" |' in
+front of the fzf. This will give you a view to scroll through related files with the same opening and linking commands
+as zk-search. Planning to add a --bind to the zks search tool.
+"""
+
+
+def vectorize_text(series):
+    """
+    Uses sklearn text vectorizer. Will do the necessary preprocessing like removing stop words,
+    transform to lowercase etc.
+
+    :param series: Pandas Series object
+    :return: matrix of tf-idf features
+    """
+    return TfidfVectorizer().fit_transform(series.values)
+
+
+def index_from_title(series, title):
+    return series[series == title].index
+
+
+def similarity_index(search_index, vectors):
+    """
+    Uses cosine similarity to find which documents are the most similar to the file index passed
+    in search_index
+    :param search_index: Index of file you want similar files to
+    :param vectors: Vector of TF-IDF vector features for each document
+    :return: Returns the index numbers of the decuments in order of similarity
+    """
+    cosine_similarities = linear_kernel(vectors[search_index], vectors).flatten()
+    return (-cosine_similarities).argsort()
+
+
+def relevant_titles(df, title, title_col, text_col):
+    """
+    Uses indexes from similarity_index to sort the DataFrame of notes by similarity
+    :param df: DataFame of notes (from zettelkasten database)
+    :param title: Title to search for similar files
+    :param title_col: Name of column in DataFrame that has titles of each note
+    :param text_col: Name of column in DataFrame that has the body of each note
+    :return: DataFrame sorted by similarity to the note title passed
+    """
+    vectors = vectorize_text(df[text_col])
+    searching_index = index_from_title(df[title_col], title)
+    sim_index = similarity_index(searching_index, vectors)
+    return df.iloc[sim_index][title_col].values
+
+
+class MyParser(argparse.ArgumentParser):
+    def error(self, message):
+        sys.stderr.write('error: %s\n' % message)
+        self.print_help()
+        sys.exit(2)
+
+
+class CustomAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        setattr(namespace, self.dest, " ".join(values))
+
+
+class TfidfSearch:
+
+    def __init__(self):
+
+        if 'ZK_PATH' in os.environ:
+            self.zk_path = os.environ['ZK_PATH']
+        else:
+            raise KeyError("ZK_PATH variable not defined! Run $ echo 'export ZK_PATH=$HOME/Zettelkasten' >> ~/.bashrc")
+
+        self.conn = sqlite3.connect(os.path.join(self.zk_path, "index.db"))
+        self.cursor = self.conn.cursor()
+        self.num_files_to_show = 20
+
+    def application_logic(self, filename):
+        df = pd.read_sql("SELECT * FROM zettelkasten WHERE title NOT LIKE 'highlights/%'", con=self.conn)
+        for file in relevant_titles(df, filename, title_col="title", text_col="body")[:self.num_files_to_show]:
+            print(file)
+
+    def run(self):
+        parser = argparse.ArgumentParser(description='Perform document similarity search based on TF-IDF')
+        parser.add_argument('filename', metavar='filename', type=str, nargs='+', action=CustomAction,
+                            help='filename to search for similarity')
+
+        if len(sys.argv) == 1:
+            parser.print_help(sys.stderr)
+            sys.exit(1)
+
+        args = parser.parse_args()
+        self.application_logic(args.filename)
+
+
+if __name__ == "__main__":
+    TfidfSearch().run()