Decision table parser
A small snippet to parse a decision table
What's a decision table?
Decision tables are a precise yet compact way to model complex rule sets and their corresponding actions.
Example
| What should I do today? | |||||
|---|---|---|---|---|---|
| Sunny | 0 | 1 | 0 | 1 | X |
| Raining | 0 | 0 | 1 | 1 | X |
| Typhoon | 0 | 0 | 0 | 0 | 1 |
| Go outside | 1 | 1 | 1 | 1 | |
| Take umbrella | 1 | 1 | |||
| Wear sunglasses | 1 | 1 | |||
| Stay home | 1 |
Usage
You must supply the list of conditions and your answers. It returns the matched column number.
EXAMPLE_DECISION_TABLE = {
:conditions => {
'sunny' => [0,1,0,1,nil],
'raining' => [0,0,1,1,nil],
'typhoon' => [0,0,0,0,1]
},
:actions => {
'go outside' => [1,1,1,1,0],
'take umbrella' => [0,0,1,1,0],
'wear sunglasses' => [0,1,0,1,0],
'stay home' => [0,0,0,0,1]
}
}
EXAMPLE_ANSWERS = [1, 0, 0]
column = DecisionTable::parse(EXAMPLE_DECISION_TABLE[:conditions], EXAMPLE_ANSWERS)
# => 1
In this example, the column is 1, therefore: go outside and wear sunglasses ;)
EXAMPLE_DECISION_TABLE[:actions].each {|x| puts x[0] if x[1][column] == 1 }
# go outside
# wear sunglasses