Return matching nested array in Ruby

Question

I have a nested "main" array and I am looking to return the results (the entire nested array) for elements matched in a second "match" array. I have been able to return the first value of the arrays desired output using (main && match) but I can find a way into the nested array.

Main:

[[111, [100,101,102]], [222, [200,201,202]], [333, [300,301,302]], [444, [400,401,402]], [555, [500,501,502]], [666, [600,601,602]], [777, [700,701,702]]]

Match:

[222,555,666]

Desired Results:

[[222, [200,201,202]], [555, [500,501,502]], [666, [600,601,602]]]

inertialgradient · Accepted Answer · 2013-11-15 03:42:40Z

4

This is a perfect place to use Array#assoc:

data = [[111, [100,101,102]], [222, [200,201,202]], [333, [300,301,302]], [444, [400,401,402]], [555, [500,501,502]], [666, [600,601,602]], [777, [700,701,702]]]
match = [222,555,666]

p match.map{|i| data.assoc(i)}

#=> [[222, [200, 201, 202]], [555, [500, 501, 502]], [666, [600, 601, 602]]]

From the docs, Array#assoc

Searches through an array whose elements are also arrays comparing obj with the first element of each contained array using obj.==.

Returns the first contained array that matches (that is, the first associated array), or nil if no match is found.

edited Nov 15, 2013 at 3:42

answered Nov 15, 2013 at 3:01

inertialgradient

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alkalinecoffee · Accepted Answer · 2013-11-15 02:53:29Z

0

Use a select to match on the first element in each of the sub-arrays:

data = [[111, [100,101,102]], [222, [200,201,202]], [333, [300,301,302]], [444, [400,401,402]], [555, [500,501,502]], [666, [600,601,602]], [777, [700,701,702]]]

match = [222, 555, 666]

results = data.select{|x| match.include?(x[0])}

p results

#=> [[222, [200, 201, 202]], [555, [500, 501, 502]], [666, [600, 601, 602]]]

answered Nov 15, 2013 at 2:53

alkalinecoffee

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