Add Array Value from Array1 if Key Matches in Array2 (Ruby)

Question

I'm trying to merge two arrays when there is a key match.

"mac" array should match "id[0]" key, and if match is true append "id[1]" value to my "ip".

For this example will use "computer", "ip address" and "mac address"

id = {
  '01:02:03:04:05:06' => 'Desktop'
  '07:08:09:10:11:12' => 'Laptop'
}

ip = { '192.168.0.10', '192.168.0.20' }
mac = { '01:02:03:04:05:06', '07:08:09:10:11:12' }

Code I'm using so far;

net = ip.zip(mac)
net.each do |ip,mac|
  puts "#{ip} / #{mac}"
end

Example output (wanted):

192.168.0.10 / 01:02:03:04:05:06 / Desktop
192.168.0.20 / 07:08:09:10:11:12 / Laptop

Tux, a few observations: 1. ip and mac are arrays, so enclose with [], not {} (plz edit); 2. it is confusing to give the (local-to-) block variables the same names as the arrays ip and mac; 3. you could chain to avoid the need for the temporary variable net (i.e., ip.zip(mac).each {|i,m| puts ... }); 4. elements of a hash cannot be identified with indices (id[0] is the value corresponding to key 0, or nil if there is no key 0), so instead say something like, "for a given element m of mac, if id contains an element with key m, then append id[m] to...". — Cary Swoveland
– Cary Swoveland, Commented Nov 12, 2013 at 18:28

Felix · Accepted Answer · 2013-11-13 05:44:26Z

2

In your example id (rename it to hostnames) is a Hash and not an Array, thus you can look up on the fly and change the line with puts to:

puts "#{ip} / #{mac} / #{id[mac]}"

Not sure if that matches your question and requirements. If so, please change the question title (hash lookup).

edited Nov 13, 2013 at 5:44

answered Nov 12, 2013 at 16:26

Felix

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2 Comments

Tux Over a year ago

I'll rename it to "host" but your example worked :-) Thank you!

Cary Swoveland Over a year ago

I was momentarily confused until it clicked that you were replacing just one line of the questioner's code. Depending what "if there is a match" means, maybe puts "#{ip}" + (id[mac] ? " / #{mac} / #{id[mac]}" : "").

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