Ruby, iterating over a multi-value Hash using if/else, trying to return key/value pairs, fails when value is not found - ruby

Question

I am trying to scan a string of raw input from a user and return a sentence that's composed of an array of arrays with the (TOKEN, WORD) pairings. If a word isn't part of the lexicon, then it should still return the WORD but set the TOKEN to an error token.
Inside the method "##dictionary.each do |type, list|" the initial if statement works fine at building a key/value array of found words, as long as the else statement is set to return nil. However, when I try and place error/words pairs into the array for the words not contained in the ##dictionary hash (i.e. those that fall into the else part of the code), I receive 5 separate pairs in the array for each word that the user entered, one for each iteration over each key for each word entered.
Does anybody have an idea how to return just one error/value pair to the array, instead of one for each of the five iterations for every word?
class Lexicon
##dictionary = {
'direction' => ['north', 'south', 'east', 'west', 'down', 'up', 'left', 'right', 'back'],
'verbs' => ['go', 'stop', 'kill', 'eat'],
'stop words' => ['the', 'in', 'of', 'on', 'at', 'it'],
'nouns' => ['door', 'bear', 'princess', 'cabinet'],
'numbers' => [0..9]
}
stuff = $stdin.gets.chomp
##words = stuff.split(' ')
def self.scan
result = []
##words.each do |text_element|
categorized = []
##dictionary.each do |type, list|
if
list.include?(text_element.downcase)
categorized = [type, text_element]
result.push(categorized)
else
nil
#categorized = ["ERROR", text_element]
#result.push(categorized)
end
end
end
print result
end
Lexicon.scan
end

Answer 1

It happens because of each iterates over all elements and it is true once or never.
This reduction of your code should help you understand what happen:
dictionary = {
'direction' => ['north', 'south'],
'verbs' => ['go', 'stop', 'kill', 'eat'],
'whathever' => ['blah']
}
text = 'go'
dictionary.each do |type, list|
if p list.include?(text) # added p
then
p text
else
p 'error'
end
end
It returns:
# false
# "error"
# true
# "go"
# false
# "error"
You need a different approach, for example:
text = 'nothing'
result = dictionary.find { |_, v| v.include? text }
result ? [result.keys, text] : "Error"

Answer 2

While it may feel organize to have the dictionary categorized by lists, this would be both simplified and much faster were the dictionary to be flattened and have a default set to the 'ERROR' token.
For example:
##dictionary = {
'direction' => ['north', 'south', 'east', 'west', 'down', 'up', 'left', 'right', 'back'],
'verbs' => ['go', 'stop', 'kill', 'eat'],
...
Becomes this:
##dictionary = {
'north' => 'direction',
'south' => 'direction',
...
'go' => 'verbs',
'stop' => 'verbs',
...
}
##dictionary.default = 'ERROR'
This way, your lookup becomes linear and without unnecessary boolean logic, like so.
def scan
result = stuff.split(' ').map do |word|
[##dictionary[word.downcase], word]
end
print result
end

Answer 3

This has worked for me. Thanks to Sebastian Scholl for the idea of simplifying the dictionary.
class Lexicon
##dictionary = {
'direction' => ['north', 'south', 'east', 'west', 'down', 'up', 'left', 'right', 'back'],
'verbs' => ['go', 'stop', 'kill', 'eat'],
'stop words' => ['the', 'in', 'of', 'on', 'at', 'it'],
'nouns' => ['door', 'bear', 'princess', 'cabinet'],
'numbers' => [0..9]
}
stuff = $stdin.gets.chomp
##words = stuff.downcase.split(' ')
def self.scan
result = []
values = []
##dictionary.each do |key, value|
values << value
end
value_list = values.flatten.uniq
##words.each do |text_element|
if value_list.include?(text_element)
##dictionary.each do |key, value|
if value.include?(text_element)
categorized = [key, text_element]
result.push(categorized)
else
nil
end
end
else
result.push(["Error, #{text_element}"])
end
end
print result
end
Lexicon.scan
end