How do I correctly access and iterate over multidimensional arrays in Ruby?

Question

I have this block of code:

super_heroes = [
    ["Spider Man", "Peter Parker"],
    ["Deadpool", "Wade Wilson"],
    ["Wolverine", "James Howlett"]
]

super_heroes.each do |sh|
    sh.each do |heroname, realname|
        puts "#{realname} is #{heroname}"
    end
end

The output is this:

 is Spider Man
 is Peter Parker
 is Deadpool
 is Wade Wilson
 is Wolverine
 is James Howlett

But I wanted to be this:

Peter Parker is Spider Man
Deadpool is Wade Wilson
Wolverine is James Howlett

After hours of iterating the code, I still couldn't figure it out. I would appreciate if someone could put me in the right direction and explain what I'm doing wrong. Thanks!

Arup Rakshit · Accepted Answer · 2014-02-17 19:48:21Z

4

Do as below :

super_heroes = [
    ["Spider Man", "Peter Parker"],
    ["Deadpool", "Wade Wilson"],
    ["Wolverine", "James Howlett"]
]

super_heroes.each do |heroname, realname|
   puts "#{realname} is #{heroname}"
end

# >> Peter Parker is Spider Man
# >> Wade Wilson is Deadpool
# >> James Howlett is Wolverine

What happened with your code ?

super_heroes.each do |sh| # sh is ["Spider Man", "Peter Parker"] etc..
    # here **heroname** is "Spider Man", "Peter Parker" etc.
    # every ietration with sh.each { .. } your another variable **realname**
    # is **nil**
    sh.each do |heroname, realname| 
        puts "#{realname} is #{heroname}"
        # as **realname** is always **nil**, you got the output as
        # is Spider Man
        # is Peter Parker
        # .....
        # .....
    end
end

edited Feb 17, 2014 at 19:48

answered Feb 17, 2014 at 18:06

Arup Rakshit

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1 Comment

Jan Over a year ago

That works! Why didn't I think of that!!! Knowing that it's a 2D array my extinct told me to maybe use .each method twice. @mdsantis: "Flash" badge indeed.

Thaha kp · Accepted Answer · 2014-02-18 07:20:13Z

1

Try this also,

super_heroes.each do |sh|
    puts sh.join(" is ")
end

answered Feb 18, 2014 at 7:20

Thaha kp

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