Hi i'am new in ruby and i want to get a Hash with string in keys and an Array in value, like this :
Hash = new HashMap
for (issue :is)
Hash.add(is.user_name)
if(hash.contains(is.user_name)) then
hash.value.add(is)
end
end
to get a result like this :
{"jane"[issue123,issue234,issue345]; "mike" [issue333,issue444,issue555]; "Alain" [issue876,issue987,issue356] }
jane have [issue123,issue234,issue345]
thanks
Something like below:
result = Hash.new { |hash, key| hash[key] = [] }
issues.each do |issue|
result[issue.user_name].push issue
end
Related
Let's say we're using .dig in Ruby like this:
some_hash = {}
some_hash.dig('a', 'b', 'c')
# => nil
which returns nil
Is there a method where I can assign a value to the key c if any of the other ones are present? For example if I wanted to set c I would have to write:
some_hash['a'] = {} unless some_hash['a'].present?
some_hash['a']['b'] = {} unless some_hash['a']['b'].present?
some_hash['a']['b']['c'] = 'some value'
Is there a better way of writing the above?
That can be easily achieved when you initialize the hash with a default like this:
hash = Hash.new { |hash, key| hash[key] = Hash.new(&hash.default_proc) }
hash[:a][:b][:c] = 'some value'
hash
#=> {:a=>{:b=>{:c=>"some value"}}}
Setting nested values in that hash with nested defaults can partly be done with dig (apart from the last key):
hash.dig(:a, :b)[:c] = 'some value'
hash
#=> {:a=>{:b=>{:c=>"some value"}}}
I have an array of hashes as json, so how to check my array of hashes contains a hash with a given key-value pair.
This is my json
[{"question"=>"0a2a3452", "answer"=>"bull"}, {"question"=>"58deacf9", "answer"=>"bullafolo"}, {"question"=>"32c53e5f", "answer"=>"curosit"}, {"question"=>"b5546bcf", "answer"=>""}, {"question"=>"0f0b314", "answer"=>""}]
I tried looping through the json array, but this is tedious, as I need to check that if that json has that hash with a given key-value pair
It's a questionnaire form, in which I have to perform an update on answers
if !#client_find.nil?
#client_find.questionnaire
params[:commit].each do |key, value|
#json=[]
#json = #client_find.questionnaire
if !value.empty? && #json.include?(key)
puts "blunderc "+ value.inspect
#new_append = Hash.new
#new_append[:question] = key
#new_append[:answer]= value
#json << #new_append
end
if !key.empty? && !value.empty?
#logic
#json.each do |u|
if (u.key? key)
puts "bothu "+ u[key].inspect
u[key] = value
end
end
end
end
Array#any? iterates through the array. In each iteration I check wether the current hash has the searched question key or not. If a hash is found Array#any? returns true otherwise false.
array = [{"question"=>"0a2a3452", "answer"=>"bull"}, {"question"=>"58deacf9", "answer"=>"bullafolo"}, {"question"=>"32c53e5f", "answer"=>"curosit"}, {"question"=>"b5546bcf", "answer"=>""}, {"question"=>"0f0b314", "answer"=>""}]
search_for_key = '0a2a3452'
array.any?{|hash| hash['question'] == search_for_key}
I'll assume that you want to check the existence of a hash which has the key/value pair "quesetion" => "some-value".
Here's how you can do it:
array.any? { |item| item['question'] == 'some-question-id' }
Considering your are checking for a particular key exists or not
#json.any? {|obj| obj.key?(your_particular_key)
You can filter the array using Enumerable#select to get only the hashes that contains the desired key.
filtered = my_hash.select { |item| item['desired_key'] }
That's possible because nil is falsey. If you input is a raw JSON you'll need to parse it to a Ruby hash using JSON#parse or any other equivalent method.
filtered will give you all the hashes that contain the desired_key.
Is that what you want ?
Btw guitarman's answer is way better !
questions = [{"question"=>"0a2a3452", "answer"=>"bull"}, {"question"=>"58deacf9", "answer"=>"bullafolo"}, {"question"=>"32c53e5f", "answer"=>"curosit"}, {"question"=>"b5546bcf", "answer"=>""}, {"question"=>"0f0b314", "answer"=>""}]
result = questions.find { |question| question['question'] == "Bonour" }
if result.nil?
puts "Not found"
else
puts "#{result['question']} #{result['answer']}"
end
I have a hash of array with key, values in ruby which I want to pass each value with key. I want to extract content using my hash. My code is :
def get_content
GetPageContent.new(#pdf.id, session[:selected_pages][#document.id.to_s])
end
in session[:selected_pages] I got like this
{"15"=>["001"], "24"=>["001","005"]}
In this first value is pdf id and second value is page number of that pdf.
I want this :
GetPageContent.new(#pdf.id, session[:selected_pages][#document.id.to_s])
I want to pass all values like this:
GetPageContent.new(15, 001)
GetPageContent.new(24, 001)
GetPageContent.new(24, 005)
How to map each key values from hash of array?
A simple nested loop will suffice:
session[:selected_pages].each do |pdf_id, page_numbers|
page_numbers.each { |page_number| GetPageContent.new(pdf_id, page_number) }
end
You can use something like this
hsh = {"15"=>["001"], "24"=>["001","005"]}
hsh.each(&->(page, pages){pages.each{|id| GetPageContent.new(id, page)}})
You could do something like this to get a simple array. h is your hash
pages = h.flat_map { |key, arr| ([key] * arr.size).zip(arr) }
=> [["15", "001"], ["24", "001"], ["24", "005"]]
pages.map! { |pdf_id, page_number| GetPageContent.new(pdf_id, page_number) }
session[:selected_pages]
.map{|k, v| [k].product(v)}.flatten(1)
# => [["15", "001"], ["24", "001"], ["24", "005"]]
The rest is up to you.
I have the following snippet of code to fetch certain columns from the db:
#data = Topic.select("id,name").where("id in (?)",#question.question_topic.split(",")).map(&:attributes)
In the resulting Array of Hashes which is :
Current:
#data = [ { "id" => 2, "name" => "Sports" }]
To be changed to:
#data = [ { "id" => "2", "name" => "Sports" }]
I want to convert "id" to string from fixnum. Id is integer in the db. What is the cleanest way to do this?
Note: After using .map(&:attributes) it is not an active record relation.
You can do it with proper map usage:
topics = Topic.select("id,name").where("id in (?)",#question.question_topic.split(","))
#data = topics.map do |topic|
{
'id' => topic.id.to_s,
'name' => topic.name
}
end
What you're looking for is simply
#data.each { |obj| obj["id"] = obj["id"].to_s }
There isn't really a simpler way (I think that's straightforward enough anyway).
Going by the title which implies a different question - converting every value in the hash to a string you can do this:
#data.each do |obj|
obj.map do |k, v|
{k => v.to_s}
end
end
Just leaving that there anyway.
You can use Ruby's #inject here:
#data.map do |datum|
new_datum = datum.inject({}) do |converted_datum, (key, value)|
converted_datum[key] = value.to_s
converted_datum
end
end
This will work to convert all values to strings, regardless of the key.
If you are using Rails it can be even cleaner with Rails' #each_with_object:
#data.map do |datum|
datum.each_with_object({}) do |(key, value), converted_datum|
converted_datum[key] = value.to_s
end
end
This will iterate all the key names in the hash and replace the value with the #to_s version of the datum associated with the key. nil's converted to empty strings. Also, this assumes you don't have complex data within the hash like embedded arrays or other hashes.
def hash_values_to_string(hash)
hash.keys.each {|k| hash[k]=hash[k].to_s}; hash
end
If I have an array of hashes, each with a day key:
[
{:day=>4,:name=>'Jay'},
{:day=>1,:name=>'Ben'},
{:day=>4,:name=>'Jill'}
]
What is the best way to convert it to a hash with sorted day values as the keys:
{
:1=>[{:day=>1,:name=>'Ben'}],
:4=>[{:day=>4,:name=>'Jay'},{:day=>4,:name=>'Jill'}]
}
I'm using Ruby 1.9.2 and Rails 3.1.1
Personally, I wouldn't bother "sorting" the keys (which amounts to ordering-by-entry-time in Ruby 1.9) until I actually needed to. Then you can use group_by:
arr = [{:day=>4,:name=>'Jay'}, {:day=>1,:name=>'Ben'}, {:day=>4,:name=>'Jill'}]
arr.group_by { |a| a[:day] }
=> {4=>[{:day=>4, :name=>"Jay"}, {:day=>4, :name=>"Jill"}],
1=>[{:day=>1, :name=>"Ben"}]}
Instead, sort the keys when you actually need them.
Assuming you array is called is list, here's one way using the reduce method:
list.reduce({}) { |hash, item|
(hash[item[:day]] ||= []) << item; hash
}
Here's another using the map method, but you have to carry a holder variable around:
hash = {}
list.each { |item|
(hash[item[:day]] ||= []) << item
}
Once you have the unsorted hash say in variable foo, you can sort it as,
Hash[foo.sort]
Simple answer:
data = [
{:day=>4,:name=>'Jay'},
{:day=>1,:name=>'Ben'},
{:day=>4,:name=>'Jill'}
]
#expected solution
sol = {
1=>[{:day=>1,:name=>'Ben'}],
4=>[{:day=>4,:name=>'Jay'},{:day=>4,:name=>'Jill'}]
}
res = {}
data.each{|h|
res[h[:day]] ||= []
res[h[:day]] << h
}
p res
p res == sol #check value
p res.keys == sol.keys #check order
Problem with this solution: The hash is not sorted as requested. (Same problem has Anurags solution).
So you must modify the answer a bit:
res = {}
data.sort_by{|h| h[:day]}.each{|h|
res[h[:day]] ||= []
res[h[:day]] << h
}
p res
p res == sol #check value
p res.keys == sol.keys #check order
In Rails you can use OrderedHash:
ActiveSupport::OrderedHash[arr.group_by { |a| a[:day] }.sort_by(&:first)]
Update: In fact in Ruby 1.9 hash is ordered, so using ActiveSupport extension is not required:
Hash[arr.group_by { |a| a[:day] }.sort_by(&:first)]