logician_query: Query a database

In dirkschumacher/logician: Logic Programming in R

Description

Query a database

Usage

logician_query(database, question)

logician_query_(database, question)

## S3 method for class 'logician_clause'
logician_query_(database, question)

## S3 method for class 'logician_r_expr'
logician_query_(database, question)

Arguments

database	a list of rules and facts
question	a clause of type logician_clause or an R expression of type logician_r_expr

Examples

database <- logician_database(
  connected(berlin, hamburg),
  connected(hamburg, chicago),
  connected(chicago, london),
  connected(aachen, berlin),
  connected(chicago, portland),
  connected(portland, munich),
  path(A, B) := connected(A, B),
  path(A, B) := connected(A, Z) && path(Z, B)
)
iter <- logician_query(database, path(berlin, hamburg))
iter$next_value()

iter <- logician_query(database, path(berlin, X))
iter$next_value()
iter$next_value()
iter$next_value()

dirkschumacher/logician documentation built on June 13, 2020, 5:11 p.m.