Updating Ruby Hash Values with Array Values

Question

I've created the following hash keys with values parsed from PDF into array:

columns = ["Sen", "P-Hire#", "Emp#", "DOH", "Last", "First"]
h = Hash[columns.map.with_index.to_h]
=> {"Sen"=>0, "P-Hire#"=>1, "Emp#"=>2, "DOH"=>3, "Last"=>4, "First"=>5}

Now I want to update the value of each key with 6 equivalent values from another parsed data array:

rows = list.text.scan(/^.+/)
row = rows[0].tr(',', '')
@data = row.split
=> ["2", "6", "239", "05/05/67", "Harp", "Erin"]

I can iterate over @data in the view and it will list each of the 6 values. When I try to do the same in the controller it sets the same value to each key:

data.each do |e|
  h.update(h){|key,v1| (e) }
end
=>
{"Sen"=>"Harper", "P-Hire#"=>"Harper", "Emp#"=>"Harper", "DOH"=>"Harper", "Last"=>"Harper", "First"=>"Harper"

So it's setting the value of each key to the last value of the looped array...

FYI: Hash[....to_h] is redundant. You can drop the Hash[], it's not doing anything, columns.map.with_index.to_h is giving you the value you're after. — user229044
– user229044 ♦, Commented Apr 1, 2017 at 0:18

moveson · Accepted Answer · 2017-04-01 00:13:35Z

4

I would just do:

h.keys.zip(@data).to_h

If the only purpose of h is as an interim step getting to the result, you can dispense with it and do:

columns.zip(@data).to_h

answered Apr 1, 2017 at 0:13

moveson

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5 Comments

DawgOnKing Over a year ago

Perfect! Thanks for the help! Remarkably useful method. It's not listed in the online docs I was using so thanks for the knowledge.

Cary Swoveland Over a year ago

This answer, imo, should have received the ✅.

DawgOnKing Over a year ago

@CarySwoveland - I agree. It has been changed.

DawgOnKing Over a year ago

This worked by supplying a single object row = rows[0].tr(',', '').split but when trying to loop through them with rows.each, the .split method fails which in turn causes the zip().to_h to also fail. Any ideas?

moveson Over a year ago

You'll need to provide more information. Please submit a new question with a detailed explanation of the setup and the error you are getting.

oreoluwa · Accepted Answer · 2017-04-01 00:11:56Z

1

There are several ways to solve this problem but a more direct and straight forward way would be:

columns = ["Sen", "P-Hire#", "Emp#", "DOH", "Last", "First"]
...
@data = row.split

h = Hash.new
columns.each_with_index do |column, index|
 h[column] = @data[index]
end

Another way:

h.each do |key, index|
  h[key] = @data[index]
end

Like I said, there are several ways of solving the issue and the best is always going to depend on what you're trying to achieve.

answered Apr 1, 2017 at 0:11

oreoluwa

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3 Comments

moveson Over a year ago

Ruby convention is to avoid each (and indexes) when other methods can achieve the same result.

oreoluwa Over a year ago

yes, you're right. But I'd rather also prefer explicitness over hidden abstractions

moveson Over a year ago

I'm all for explicitness, but how is zip more hidden or abstract than index or each? This seems to be precisely the use case for zip followed by to_h.

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