Renamed tabular

24-persistent-tables/README.md

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+Style #24
+==============================
+
+Constraints:
+
+- The input data of the problem is modeled as entities with relations between them
+
+- The data is placed in tables, with columns potentially cross-referencing data in other tables
+
+- Existence of a relational query engine
+
+- The problem is solved by issuing queries over the tabular data
+
+Possible names:
+
+- Tabular
+- Flatland
+- Relational

24-persistent-tables/tf-24.py

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+#!/usr/bin/env python
+import sys, re, string, sqlite3, os.path
+
+#
+# The relational database of this problem consists of 3 tables:
+# documents, words, characters
+#
+def create_db_schema(connection):
+    c = connection.cursor()
+    c.execute('''CREATE TABLE documents (id INTEGER PRIMARY KEY AUTOINCREMENT, name)''')
+    c.execute('''CREATE TABLE words (id, doc_id, value)''')
+    c.execute('''CREATE TABLE characters (id, word_id, value)''')
+    connection.commit()
+    c.close()
+
+def load_file_into_database(path_to_file, connection):
+    """ Takes the path to a file and loads the contents into the database """
+    def _extract_words(path_to_file):
+        with open(path_to_file) as f:
+            str_data = f.read()    
+        pattern = re.compile('[\W_]+')
+        word_list = pattern.sub(' ', str_data).lower().split()
+        with open('../stop_words.txt') as f:
+            stop_words = f.read().split(',')
+        stop_words.extend(list(string.ascii_lowercase))
+        return [w for w in word_list if not w in stop_words]
+
+    words = _extract_words(path_to_file)
+
+    # Now let's add data to the database
+    # Add the document itself to the database
+    c = connection.cursor()
+    c.execute("INSERT INTO documents (name) VALUES (?)", (path_to_file,))
+    c.execute("SELECT id from documents WHERE name=?", (path_to_file,))
+    doc_id = c.fetchone()[0]
+
+    # Add the words to the database
+    c.execute("SELECT MAX(id) FROM words")
+    row = c.fetchone()
+    word_id = row[0]
+    if word_id == None:
+        word_id = 0
+    for w in words:
+        c.execute("INSERT INTO words VALUES (?, ?, ?)", (word_id, doc_id, w))
+        # Add the characters to the database
+        char_id = 0
+        for char in w:
+            c.execute("INSERT INTO characters VALUES (?, ?, ?)", (char_id, word_id, char))
+            char_id += 1
+        word_id += 1
+    connection.commit()
+    c.close()
+
+#
+# Create if it doesn't exist
+#
+if not os.path.isfile('tf.db'):
+    with sqlite3.connect('tf.db') as connection:
+        create_db_schema(connection)
+        load_file_into_database(sys.argv[1], connection)
+
+# Now, let's query
+with sqlite3.connect('tf.db') as connection:
+    c = connection.cursor()
+    c.execute("SELECT value, COUNT(*) as C FROM words GROUP BY value ORDER BY C DESC")
+    for i in range(25):
+        row = c.fetchone()
+        if row != None:
+            print row[0] + ' - '  + str(row[1])