How to parse .ttl files with RDFLib?

Question

I have a file in .ttl form. It has 4 attributes/columns containing quadruples of the following form:

1. (id, student_name, student_address, student

Answer 1

Turtle is a subset of Notation 3 syntax so rdflib should be able to parse it using format='n3'. Check whether rdflib preserves comments (ids are specified in the comments (#...) in your sample). If not and the input format is as simple as shown in your example then you could parse it manually:

import re
from collections import namedtuple
from itertools import takewhile

Entry = namedtuple('Entry', 'id name address phone')

def get_entries(path):
    with open(path) as file:
        # an entry starts with `#@` line and ends with a blank line
        for line in file:
            if line.startswith('#@'):
                buf = [line]
                buf.extend(takewhile(str.strip, file)) # read until blank line
                yield Entry(*re.findall(r'<([^>]+)>', ''.join(buf)))

print("\n".join(map(str, get_entries('example.ttl'))))

Output:

Entry(id='id1', name='Alice', address='USA', phone='12345')
Entry(id='id1', name='Jane', address='France', phone='78900')

To save entries to a db:

import sqlite3

with sqlite3.connect('example.db') as conn:
    conn.execute('''CREATE TABLE IF NOT EXISTS entries
             (id text, name text, address text, phone text)''')
    conn.executemany('INSERT INTO entries VALUES (?,?,?,?)',
                     get_entries('example.ttl'))

To group by id if you need some postprocessing in Python:

import sqlite3
from itertools import groupby
from operator import itemgetter

with sqlite3.connect('example.db') as c:
    rows = c.execute('SELECT * FROM entries ORDER BY id LIMIT ?', (10,))
    for id, group in groupby(rows, key=itemgetter(0)):
        print("%s:\n\t%s" % (id, "\n\t".join(map(str, group))))

Output:

id1:
    ('id1', 'Alice', 'USA', '12345')
    ('id1', 'Jane', 'France', '78900')