Ruby: Array of Arrays to Array of Hashes - ruby

Question

I have an Array of Arrays (imported from CSV file):
[[title1],[title2],[title3],[title4],[title5]],
[[song1],[author1],[bpm1],[key1],[energy1]],
...
[[song100],[author100],[bpm100],[key100],[energy100]].
and would like to convert it to an Array of Hashes like:
[{"title1"=>"song1","title2"=>"author1","title3"=>"bpm1","title4"=>"key1","title5"=>"energy1"}],
...
[{"title1"=>"song100","title2"=>"author100","title3"=>"bpm100","title4"=>"key100","title5"=>"energy100"}].
I used the code below but it doesn't work:
require 'csv'
csv=CSV.read('library.csv')
array_hash=[]
hash={}
for i in 1..(csv.size)
hash1={}
for n in 0..4
a=csv[0][n]
b=csv[i][n]
hash1[a]=b
hash.merge!(hash1)
end
array_hash.push(hash)
end
But I get:
> NoMethodError: undefined method `[]' for nil:NilClass from
> (irb):149:in `block (2 levels) in irb_binding' from (irb):146:in
> `each' from (irb):146:in `block in irb_binding' from (irb):143:in
> `each' from (irb):143 from
> /Users/user/.rvm/rubies/ruby-2.0.0-p481/bin/irb:12:in `<main>'
What is wrong with this?
How to do the same using .each ?

Answer 1

The ruby CSV library has a to_hash function on CSV::Row, so you can do as below instead:
require 'csv'
rows = CSV.read('library.csv', headers: true).map(&:to_hash) #rows would return a list of hashes