Database/CSV knowledge base¶

Using data from an SQLite database¶

ProbLog provides a library that offers a very simple interface to an SQLite database.

Assume we have an SQLite database friends.db with two tables:

person(name)

A list of persons.

friend_of(name1, name2, probability)

A list of friendship relations.

We can load this database into ProbLog using the library db and the predicate sqlite_load(+Filename).

:- use_module(library(db)).
:- sqlite_load('friends.db').

This will create a predicate for each table in the database with as arity the number of columns of that table. We can thus write the following variation of the smokers examples:

:- use_module(library(sqlite)).
:- sqlite_load('friends.db').

P :: influences(X, Y) :- friend_of(X, Y, P).

0.3::smokes(X) :- person(X).       % stress
smokes(X) :- influences(Y, X), smokes(Y).

The library will automatically translate a call to a database predicate into a query on the database, for example, the call friend_of(ann, B, P) will be translated to the query

SELECT name1, name2, probability FROM friend_of WHERE name1 = 'ann'

Using data from a CSV file¶

ProbLog provides a library that offers a simple interface to an CSV file.

Assume we have two CSV files person.csv and friend_of.csv containing data for two predicates:

person(name)

A list of persons.

friend_of(name1, name2, probability)

A list of friendship relations.

These file contain as columns the terms of the predicate and the first line are the column names.

$ cat person.csv
"name"
"ann"
"bob"
$ cat friend_of.csv
"p1","p2","prob"
"ann","bob",0.2

We can load these files into ProbLog using the library db and the predicate csv_load(+Filename, +Predicatename).

:- use_module(library(db)).
:- csv_load('person.csv', 'person').
:- csv_load('friend_of.csv', 'friend_of').

This will create a two predicates, one for each file with as arity the number of columns. We can thus write the following variation of the smokers examples:

:- use_module(library(db)).
:- csv_load('person.csv', 'person').
:- csv_load('friend_of.csv', 'friend_of').

P :: influences(X, Y) :- friend_of(X, Y, P).

0.3::smokes(X) :- person(X).       % stress
smokes(X) :- influences(Y, X), smokes(Y).

The library will automatically translate a call to predicates person and friends_of into a query on the respective csv-file. For example, the call friend_of(ann, B, P) will be matched to all lines that match

"ann",*,*