Let's say I want to access the values of a hash like this:
munsters = {
"Herman" => { "age" => 32, "gender" => "male" },
"Lily" => { "age" => 30, "gender" => "female" },
"Grandpa" => { "age" => 402, "gender" => "male" },
"Eddie" => { "age" => 10, "gender" => "male" },
"Marilyn" => { "age" => 23, "gender" => "female"}
}
I could use #each with two parameters:
munsters.each do |key, value|
puts "#{name} is a #{value["age"]}-year-old #{value["gender"]}."
end
Or I could use #each_pair with two parameters:
munsters.each_pair do |key, value|
puts "#{name} is a #{value["age"]}-year-old #{value["gender"]}."
end
Perhaps the difference between the two is not borne out in this simple example, but can someone help me to understand the advantage of using #each_pair over #each ?
Because Hash is an Enumerable, it has to have an each method. each_pair may be a clearer name, since it strongly suggests that two-element arrays containing key-value pairs are passed to the block.
They are aliases for each other: they share the same source code.
Related
data = [
"Company one" => {
"number_1" => 46,
"number_2" => 3055,
"country" => "USA"
},
"Company two" => {
"number_1" => 32,
"number_2" => 6610,
"country" => "USA"
},
"Company three" => {
"number_1" => 40,
"number_2" => 9128,
"country" => "USA"
}
]
So I have this array in which I'm trying to get which of the company has the biggest number in 'number_2'. The largest would be Company three with 9128.
So I have this code that puts the largest number which would be 9128
def number(data)
collected_array=[]
data.each do |company_hash|
collected_array = company_hash.map do |k,v|
v["number_2"]
end
end
puts collected_array.max
end
number(data)
But I'm trying to puts the company name with the largest number which would be "Company three". I've tried .keys and other ways but it gives me error.
I've tried this way:
def number(data)
collected_array=[]
data.each do |company_hash|
collected_array = company_hash.map do |k,v|
v["number_2"]
k
end
end
puts collected_array.max
end
number(data)
but it gives me "Company two" rather than "Company three" which would be the company with the highest number
As stated by #Cary, it can be simplified accessing the first element on data, and there using max_by, on the hash local variable available within the block checking the number_2 key value.
As the result is an Array containing two elements, the first one is the company name, the second and last one, the hash containing its data:
data = [
"Company one" => {
"number_1" => 46,
"number_2" => 3055,
"country" => "USA"
},
"Company two" => {
"number_1" => 32,
"number_2" => 6610,
"country" => "USA"
},
"Company three" => {
"number_1" => 40,
"number_2" => 9128,
"country" => "USA"
}
]
max_company = data.first.max_by { |_, h| h['number_2'] }
p max_company.first # "Company three"
p max_company.last['number_2'] # 9128
I have a list of objects that have key attribute and value attribute.
I would like to convert it to an object that contains attributes named as keys with the values.
Example will make it clearer...
This
[{
:key => "key1",
:value => "value1"
}, {
:key => "key2",
:value => "value2"
}]
Should become like this:
{
:key1 => "value1"
:key2 => "value2"
}
I'm sure there is one line to make it happen
Thanks
Using Hash::[], Array#map:
a = [{
:key => "key1",
:value => "value1"
}, {
:key => "key2",
:value => "value2"
}]
Hash[a.map { |h| [h[:key], h[:value]] }]
# => {"key1"=>"value1", "key2"=>"value2"}
Hash[a.map { |h| h.values_at(:key, :value) }]
# => {"key1"=>"value1", "key2"=>"value2"}
Hash[a.map { |h| [h[:key].to_sym, h[:value]] }]
# => {:key1=>"value1", :key2=>"value2"}
a.each_with_object({}) {|h,g| g.update({h[:key].to_sym => h[:value]}) }
# => {:key1=>"value1", :key2=>"value2"}
Hash[array.map(&:values)]
#=> {"key1"=>"value1", "key2"=>"value2"}
Just to promote the to_h a bit:
[{
:key => "key1",
:value => "value1"
}, {
:key => "key2",
:value => "value2"
}].map(&:values).map{|k,v| [k.to_sym,v]}.to_h
# => {:key1=>"value1", :key2=>"value2"}
I am struggling with some arrays with hashes inside. I want to parse them into a new object but have no idea how to do this.
Here is the data:
[
{
"name" => "itemHref",
"value" => "https://192.168.75.145:8281/api/workflows/16da1fa1-7c8b-4602-8d53-17fc5e1fa3ff/"
},
{
"name" => "id",
"value" => "16da1fa1-7c8b-4602-8d53-17fc5e1fa3ff"
},
{
"name" => "categoryName",
"value" => "FinanzInformatik"
},
{
"name" => "canExecute",
"value" => "true"
},
{
"name" => "categoryHref",
"value" => "https://192.168.75.145:8281/api/catalog/System/WorkflowCategory/ff8080813b90a145013b90cac51b0006/"
},
{
"name" => "description",
"value" => "bekommt alle VMs"
},
{
"name" => "name",
"value" => "getAllVms"
},
{
"name" => "type",
"value" => "Workflow"
},
{
"name" => "canEdit",
"value" => "true"
}
]
And, here is my code:
require 'rest-client'
require 'json'
class Workflow
def initialize(itemHref, id, categoryName, canExecute, categoryHref, description, name, type, canEdit)
#itemHref = itemHref
#id = id
#categoryName = categoryName
#canExecute = canExecute
#categoryHref = categoryHref
#description = description
#name = name
#type = type
#canEdit = canEdit
end
end
json_string = RestClient.get( "http://vcoadmin:vcoadmin#192.168.75.145:8280/api/workflows", :content_type => 'application/json', :accept => 'application/json')
parsed = JSON.parse(json_string)
parsed.each do |a, b|
if(b.class == Array)
b.flatten.each do |c|
p c['attributes']
#c['attributes'].each
{
|f| p f['name'], f['value'] }
end
end
end
How do I put the hash value into the object? I think about something based on the 'name' which is the identifier for the value.
Any ideas?
Assuming that the order of attributes shouldn't be changed:
Workflow.new(*parsed.map {|attr| attr['value']})
I would implement a PORO that can be initialized with a hash. So then you are able to pass your hash directly in to creating the workflow.
An example of this is can be seen: http://pullmonkey.com/2008/01/06/convert-a-ruby-hash-into-a-class-object/
a = {"rows" => [{"id" => "231-z", "name" => 'jon', "age"=> 27, "state" => 'AL'},
{"id" => "4121-x", "name" => 'ton', "age"=> 37, "state" => 'VA'}
]
}
b = {"rows" => [{"key" => ["xyz","4121-x"], "value" =>{"sum" => 12312, "realage" => 29}},
{"key" => ["xyz","231-z"], "value" =>{"sum" => 1212, "realage" => 33}}
]
}
In hash a, age is incorrect
In hash b, realage is correct. Also in hash b id is the second value in the first array that maps to id of hash a . Those are 4121-x, 231-z correspond to hash a
I want to correct the age in hash a and swap it with the realage of hash b
I can do it in multiple steps, but is it possible to do it in one liner or very short? So finally correct hash a should look like
a = {"rows" => [{"id" => "231-z", "name" => 'jon', "age"=> 33, "state" => 'AL'},
{"id" => "4121-x", "name" => 'ton', "age"=> 29, "state" => 'VA'}
]
}
does this look reasonable?
a['rows'].each_with_index do |ah, i|
(bh = b['rows'].select {|h| h['key'].last == ah['id'] }.first) &&
a['rows'][i] = ah.update('age' => bh['value']['realage'])
end
p a
{
"rows" => [
[0] {
"id" => "231-z",
"name" => "jon",
"age" => 33,
"state" => "AL"
},
[1] {
"id" => "4121-x",
"name" => "ton",
"age" => 29,
"state" => "VA"
}
]
}
Please note it will update a only if corresponding id found in b.
Also, the rows order does not matter, nor matter the rows number, it is only important b to have a row with same id as processed row in a
Here is a Working Demo
I have a JSON object that looks like the following:
{
"XXX":{"name":"First"},
"YYY":{"name":"Second"},
....
}
I need to render it to look like:
<div>
<h1>XXX</h1>
<p>First</p>
</div>
<div>
<h1>YYY</h1>
<p>Second</p>
</div>
....
How will I accomplish this using Mustache? The problem I am facing is that I don't know how to reference the items because the key names are arbitrary.
Convert the JSON to a hash using your favorite JSON parser, that will give you something that looks like this:
json = {
"XXX" => {"name" => "First"},
"YYY" => {"name" => "Second"},
"ZZZ" => {"name" => "Third"}
}
Then simply rearrange it into a list of little hashes with known keys:
for_mustache = json.keys.inject([ ]) do |a, k|
a.push({ :k => k, :v => json[k]['name']})
a
end
There are probably cleverer ways to do that above. Now you'll have something simple and regular like this in for_mustache:
[
{ :k => "XXX", :v => "First" },
{ :k => "YYY", :v => "Second" },
{ :k => "ZZZ", :v => "Third" }
]
Then you can handle that data structure just like any other array of hashes in Mustache:
{{#for_mustache}}
<div>
<h1>{{k}}</h1>
<p>{{v}}</p>
</div>
{{/for_mustache}}