How to group an array in the fastest way? [closed] - ruby

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I am grouping array items using the below code but it feels slow.
Is there a faster/better way to group?
#tasks_sorted = #tasks.group_by(&:start_date).map do |month, data|
hash = {"date" => month}
data.each {|placement| hash["tasks"] = data}
hash
end

I think below you are looking for :
#tasks_sorted = #tasks.group_by(&:start_date).map do |month, data|
{"date" => month, "tasks" => data }
end

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Data Parsing in Ruby [closed]

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I like to parse data like:
data = [{"dev_type"=>[{"rate"=>1000, "class_type"=>"2020"}], "sys_type"=>{"techs"=>[{"tech"=>"2", "type"=>"classA"}]}, "MOD"=>[{"id"=>"00:00:00:08:00:00", "add"=> "0"}], "user"=>"test", "host_id"=>1, "SYSTEM"=>2}]
for instance if i like to extract "rate" in dev_type.
data.each do |d|
pp d["dev_type"][0]["rate"]
end
# >> 1000
same to extract for type in sys_type i need:
data.each do |d|
pp d["sys_type"]["techs"][0]["type"]
end
# >> ClassA
But this i think not the right way doing for extracting data, what i wanted to do is to extract values like "type" in sys_type, "rate" in dev_type, "id" and "add" in MOD , and "user" . What is the best way of doing this.

How to get the index of a key in a ruby hash? [closed]

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If I have
footnotes = { "apple" => "is a fruit", "cat" => "is an animal", "car" => "a transport"}
How can I get the index of these?, something like:
footnotes["cat"].index
# => 1
There's no need to first retrieve the keys:
footnotes.find_index { |k,_| k== 'cat' } #=> 1
As to the question of whether hash key-value pairs have an index (since v1.9), I would just point out that the Ruby monks decided to supply us with Enumerable#find_index, which of course means Hash.instance_methods.include?(:find_index) #=> true.
You can do
footnotes.to_a.index {|key,| key == 'cat'}
# => 1

How can I print out the value of each key in a hash represented by *'s? [closed]

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Here is my code:
class String
def frequency
chars.each_with_object(Hash.new(0)) do |char, h|
h["#{char.upcase}:"] += 1 if char[/[[:alpha:]]/]
end
end
end
I've tried breaking it down in smaller bit's of code, such as using a .times do loop but I couldn't figure it out
for example:
str = "\*"
h["A:"] = count('a').times do
str
end
Are you trying to do something like:
counts = 'aassssvvvvv'.frequency
counts.each{|key,count| puts key + '*'*count}
# A:**
# S:****
# V:*****
Or if you want to change the key you can do:
counts.each{|key,amount| counts[key] = '*'*amount}

Assign hash values in a method [closed]

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Say I have this method
def foo(bar1, bar2)
## code
end
How could I implement the code so that, when I call foo('hello', 'world'), the foo method accesses a hash, giving:
{
:bar1 => 'hello',
:bar2 => 'world'
}
Is there a Ruby (Rails?) built in method, or how could I write it?
def foo(bar1, bar2)
names = method(__method__).parameters.map{|e| e[1]}
Hash[names.zip(names.map {|name| eval(name)})]
end
Don't do that. It's ugly and evil. Give me the whole context, you're doing something wrong.
def foo(bar1, bar2)
{bar1: bar1, bar2: bar2}
end
If what Sergio mentions was the intention of the question, then
def foo(bar1, bar2)
Hash[method(__method__).parameters.map{|_, k| [k, eval(k.to_s)]}]
end

ruby metaprogramming better solution [closed]

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How this will work without eval
%w{user_id for_whom_id category_id product_status_id}.each do |f|
code = <<-C
it "should fail validation with no #{f}" do
should_fail_on_validation { |p| p.#{f} = nil }
end
C
eval code
end
?
This should work:
%w{user_id for_whom_id category_id product_status_id}.each do |f|
it "should fail validation with no #{f}" do
should_fail_on_validation { |p| p.public_send "#{f}=", nil }
end
end
It's best to avoid the eval if possible. And in this case, it isn't necessary.

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