Convert Array to Hash in ruby with following structure

Question

I have a following array which displays information of users and some values related to the user. Following array contains information of two users Akiyo Riggs and Bingo

a1 = [["Akiyo Riggs", -32, "OverTime Hours", "",12],["Akiyo Riggs", -32, 
"Regular Hours", "", 18],["Bingo",-12,"OverTime Hours","",14], ["Bingo",
-12,"Regular Hours","",32]]

How can i convert into following array of hashes in which key is the user name and value is a hash with respective values

[{"Akiyo Riggs"=>{"OverTime Hours"=>["", 12], "Regular Hours"=>["", 18]},
{"Bingo"=>{"OverTime Hours"=>["", 14], "Regular Hours"=>["", 32]}]

You can do it in many ways. But what have you tried already ? Can u show us the code so we could help in fixing it ? — Pramod Solanky
– Pramod Solanky, Commented Dec 8, 2014 at 12:25

ncwrch · Accepted Answer · 2017-07-10 14:11:17Z

4

a1.map { |x,_,p,*ps| {x => {p => ps} } }.reduce({}, :deep_merge)
# => {"Akiyo Riggs"=>{"OverTime Hours"=>["", 12], "Regular Hours"=>["", 18]},
#     "Bingo"=>{"OverTime Hours"=>["", 14], "Regular Hours"=>["", 32]}}

Note: if efficiency is concerned, consider using deep_merge! instead of deep_merge, so that reduce wouldn't create a new hash on every iteration.

Some explanation:

a1.map { |x,_,p,*ps| {x => {p => ps} } }

gives us an array of hashes like this

 [{"Akiyo Riggs"=>{"OverTime Hours"=>["", 12]}},
  {"Akiyo Riggs"=>{"Regular Hours"=>["", 18]}},
  {"Bingo"=>{"OverTime Hours"=>["", 14]}},
  {"Bingo"=>{"Regular Hours"=>["", 32]}}]

which we can recursively merge with ActiveSupport Hash#deep_merge

edited Jul 10, 2017 at 14:11

answered Dec 8, 2014 at 12:37

ncwrch

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4 Comments

Alexander Over a year ago

Author asked for Array, but you return hash.

Mark Thomas Over a year ago

The hash form is arguably more useful.

Alexander Over a year ago

@MarkThomas of course, but that's still not an answer to author's question. btw this variant is 2 times slower that others.

Mark Thomas Over a year ago

Well I still think it qualifies as a good answer, as it is likely to get OP started on a solution.

Малъ Скрылевъ · Accepted Answer · 2014-12-08 12:35:32Z

2

You can do something like this (however, this is not quite that is you want exactly):

res = a1.group_by {|x| x[0] }.reduce({}) {|h, x| h[ x[0] ] = x[1].reduce({}) {|hh, xx| hh[ xx[2] ] = xx[3..-1] ; hh } ; h }
# => {"Akiyo Riggs"=>{"OverTime Hours"=>["", 12], "Regular Hours"=>["", 18]}, "Bingo"=>{"OverTime Hours"=>["", 14], "Regular Hours"=>["", 32]}}

the exact thing is doing with additional step:

res.keys.map {|k| {k => res[k]}}
# => [{"Akiyo Riggs"=>{"OverTime Hours"=>["", 12], "Regular Hours"=>["", 18]}}, {"Bingo"=>{"OverTime Hours"=>["", 14], "Regular Hours"=>["", 32]}}]

edited Dec 8, 2014 at 12:35

answered Dec 8, 2014 at 12:12

Малъ Скрылевъ

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1 Comment

Rajarshi Das Over a year ago

is it the best way @Malo

Alexander · Accepted Answer · 2014-12-08 12:50:23Z

1

a1.each_with_object({}) do |array, result|
  result[array[0]] ||= {}
  result[array[0]].merge!(array[2] => [array[3], array[4]])
end.map { |k, v| { k => v } }

# => [{"Akiyo Riggs"=>{"OverTime Hours"=>["", 12], "Regular Hours"=>["", 18]}}, {"Bingo"=>{"OverTime Hours"=>["", 14], "Regular Hours"=>["", 32]}}]

edited Dec 8, 2014 at 12:50

answered Dec 8, 2014 at 12:19

Alexander

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Comments

humza · Accepted Answer · 2014-12-08 22:13:42Z

1

array.each_with_object({}) do |(name, _, hours_type, a, b), hash|
  hash[name] ||= {}
  hash[name][hours_type] = [a, b]
end.map do |name, values_hash|
  {name => values_hash}
end

edited Dec 8, 2014 at 22:13

answered Dec 8, 2014 at 22:07

humza

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