This is my first time using Ruby, and I need to use the inject method to create a hash from a given array. This code pretty closely mirrors several tutorials I've found, but get an undefined method `[]=' for nil:NilClass error when executing. Am I missing anything here?
def int_hash()
[[:key1, "value1"], [:key2, "value2"]].inject({}) do |hash, element|
hash[element.first] = element.last
puts hash
end
end
int_hash()
Since puts is the last statement in the block and it returns nil, nil is returned causing the accumulator hash to be nil in the second iteration. You should return the hash. And you should pass the array as an argument to the inj_hash method to make it reusable.
def inj_hash(arr)
arr.inject({}) do |hash, element|
hash[element.first] = element.last
hash
end
end
inj_hash([[:key1, "value1"], [:key2, "value2"]])
#=> {:key1=>"value1", :key2=>"value2"}
The simplest solution to create a hash from an array of key-value pairs is to use Hash::[].
arr = [[:key1, "value1"], [:key2, "value2"]]
Hash[arr]
#=> {:key1=>"value1", :key2=>"value2"}
Hash#merge! ([[:key1, "value1"], [:key2, "value2"]].inject({}) { |hash, element| hash.merge!(element.first => element.last) }) or even Array#to_h ([[:key1, "value1"], [:key2, "value2"]].to_h). But this looks like an Enumerable#inject exercise so your first one of my merge! version are probably the most appropriate.
p hash. As opposed to puts it returns the passed argument(s).
...do |hash, (k, v)| hash[k] = v...This makes use of array decomposition, which is a powerful and useful language feature.