Hash: no implicit conversion of String into Integer-CodePudding

In ruby if I have a CSV file called, vehicles.csv:

make,model,color,doors           
dodge,charger,black,4           
ford,focus,blue,5             
nissan,350z,black,2                          
mazda,miata,white,2            
honda,civid,brown,4           
corvette,stingray,red,2            
ford,fiesta,blue,5

This is my code:

require "csv"
file = CSV.open("vehicles.csv", headers: :first_row).map(&:to_h)
puts file["make"]

I turn this csv file into a hash and then try to output one of the keys of the hash but keep getting "no implicit conversion of String into Integer" what must be done? I am trying to get something that looks like this as the output:

dodge
ford
nissan
mazda
honda
corvette
ford

CodePudding user response：

file = CSV.open("vehicles.csv", headers: :first_row).map(&:to_h) leaves file as an array of hashes. Try this to see what I mean.

require "csv"
file = CSV.open("vehicles.csv", headers: :first_row).map(&:to_h)
puts file.class
puts file.first.class
puts file.first
puts file.map {_1["make"]}

Another way to accomplish what you want is read the csv file into a table and then use the values_at method to get all the data in a given column

file = CSV.open("vehicles.csv", headers: :first_row)
table = file.read
puts table.values_at("make")