I've got a class that looks like this that turns a collection into a nested array of hashes:
# variable_stack.rb
class VariableStack
def initialize(document)
#document = document
end
def to_a
#document.template.stacks.map { |stack| stack_hash(stack) }
end
private
def stack_hash(stack)
{}.tap do |hash|
hash['stack_name'] = stack.name.downcase.parameterize.underscore
hash['direction'] = stack.direction
hash['boxes'] = stack.boxes.indexed.map do |box|
box_hash(box)
end.reverse_if(stack.direction == 'up') # array extensions
end.delete_if_key_blank(:boxes) # hash extensions
end
def box_hash(box)
{}.tap do |hash|
hash['box'] = box.name.downcase.parameterize.underscore
hash['content'] = box.template_variables.indexed.map do |var|
content_array(var)
end.join_if_any?
end.delete_if_key_blank(:content)
end
def content_array(var)
v = #document.template_variables.where(master_id: var.id).first
return unless v
if v.text.present?
v.text
elsif v.photo_id.present?
v.image.uploaded_image.url
else
''
end
end
end
# array_extensions.rb
class Array
def join_if_any?
join("\n") if size.positive?
end
def reverse_if(boolean)
reverse! if boolean
end
end
# hash_extensions.rb
class Hash
def delete_if_key_blank(key)
delete_if { |_, _| key.to_s.blank? }
end
end
This method is supposed to return a hash that looks like this:
"stacks": [
{
"stack_name": "stack1",
"direction": "down",
"boxes": [
{
"box": "user_information",
"content": "This is my name.\n\nThis is my phone."
}
},
{
"stack_name": "stack2",
"direction": "up",
"boxes": [
{
"box": "fine_print",
"content": "This is a test.\n\nYeah yeah."
}
]
}
Instead, often the boxes key is null:
"stacks": [
{
"stack_name": "stack1",
"direction": "down",
"boxes": null
},
{
"stack_name": "stack2",
"direction": "up",
"boxes": [
{
"box": "fine_print",
"content": "This is a test.\n\nYeah yeah."
}
]
}
I suspect it's because I can't "single-line" adding to arrays in Rails 5 (i.e., they're frozen). The #document.template.stacks is an ActiveRecord collection.
Why can't I map records in those collections into hashes and add them to arrays like hash['boxes']?
The failing test
APIDocumentV3 Instance methods #stacks has the correct content joined and indexed
Failure/Error:
expect(subject.stacks.first['boxes'].first['content'])
.to include(document.template_variables.first.text)
expected "\n" to include "#1"
Diff:
## -1,2 +1 ##
-#1
The presence of \n means the join method works, but it shouldn't join if the array is empty. What am I missing?
reverse_if returns nil if the condition is false. Consider this:
[] if false #=> nil
You could change it like this:
def reverse_if(condition)
condition ? reverse : self
end
delete_if_key_blank doesn't look good for me. It never deletes anything.
Disclaimer. I don't think it's a good idea to extend standard library.
So thanks to Danil Speransky I solved this issue, although what he wrote doesn't quite cover it.
There were a couple of things going on here and I solved the nil arrays with this code:
hash['boxes'] = stack.boxes.indexed.map do |box|
box_hash(box) unless box_hash(box)['content'].blank?
end.reverse_if(stack.direction == 'up').delete_if_blank?
end
That said, I'm almost certain my .delete_if_blank? extension to the Array class isn't helping at all. It looks like this, FYI:
class Array
def delete_if_blank?
delete_if(&:blank?)
end
end
I solved it by thowing the unless box_hash(box)['content'].blank? condition on the method call. It ain't pretty but it works.
I want to dynamically create a Hash without overwriting keys from an array of arrays. Each array has a string that contains the nested key that should be created. However, I am running into the issue where I am overwriting keys and thus only the last key is there
data = {}
values = [
["income:concessions", 0, "noi", "722300", "purpose", "refinancing"],
["fees:fee-one", "0" ,"income:gross-income", "900000", "expenses:admin", "7500"],
["fees:fee-two", "0", "address:zip", "10019", "expenses:other", "0"]
]
What it should look like:
{
"income" => {
"concessions" => 0,
"gross-income" => "900000"
},
"expenses" => {
"admin" => "7500",
"other" => "0"
}
"noi" => "722300",
"purpose" => "refinancing",
"fees" => {
"fee-one" => 0,
"fee-two" => 0
},
"address" => {
"zip" => "10019"
}
}
This is the code that I currently, have how can I avoid overwriting keys when I merge?
values.each do |row|
Hash[*row].each do |key, value|
keys = key.split(':')
if !data.dig(*keys)
hh = keys.reverse.inject(value) { |a, n| { n => a } }
a = data.merge!(hh)
end
end
end
The code you've provided can be modified to merge hashes on conflict instead of overwriting:
values.each do |row|
Hash[*row].each do |key, value|
keys = key.split(':')
if !data.dig(*keys)
hh = keys.reverse.inject(value) { |a, n| { n => a } }
data.merge!(hh) { |_, old, new| old.merge(new) }
end
end
end
But this code only works for the two levels of nesting.
By the way, I noted ruby-on-rails tag on the question. There's deep_merge method that can fix the problem:
values.each do |row|
Hash[*row].each do |key, value|
keys = key.split(':')
if !data.dig(*keys)
hh = keys.reverse.inject(value) { |a, n| { n => a } }
data.deep_merge!(hh)
end
end
end
values.flatten.each_slice(2).with_object({}) do |(f,v),h|
k,e = f.is_a?(String) ? f.split(':') : [f,nil]
h[k] = e.nil? ? v : (h[k] || {}).merge(e=>v)
end
#=> {"income"=>{"concessions"=>0, "gross-income"=>"900000"},
# "noi"=>"722300",
# "purpose"=>"refinancing",
# "fees"=>{"fee-one"=>"0", "fee-two"=>"0"},
# "expenses"=>{"admin"=>"7500", "other"=>"0"},
# "address"=>{"zip"=>"10019"}}
The steps are as follows.
values = [
["income:concessions", 0, "noi", "722300", "purpose", "refinancing"],
["fees:fee-one", "0" ,"income:gross-income", "900000", "expenses:admin", "7500"],
["fees:fee-two", "0", "address:zip", "10019", "expenses:other", "0"]
]
a = values.flatten
#=> ["income:concessions", 0, "noi", "722300", "purpose", "refinancing",
# "fees:fee-one", "0", "income:gross-income", "900000", "expenses:admin", "7500",
# "fees:fee-two", "0", "address:zip", "10019", "expenses:other", "0"]
enum1 = a.each_slice(2)
#=> #<Enumerator: ["income:concessions", 0, "noi", "722300",
# "purpose", "refinancing", "fees:fee-one", "0", "income:gross-income", "900000",
# "expenses:admin", "7500", "fees:fee-two", "0", "address:zip", "10019",
# "expenses:other","0"]:each_slice(2)>
We can see what values this enumerator will generate by converting it to an array.
enum1.to_a
#=> [["income:concessions", 0], ["noi", "722300"], ["purpose", "refinancing"],
# ["fees:fee-one", "0"], ["income:gross-income", "900000"],
# ["expenses:admin", "7500"], ["fees:fee-two", "0"],
# ["address:zip", "10019"], ["expenses:other", "0"]]
Continuing,
enum2 = enum1.with_object({})
#=> #<Enumerator: #<Enumerator:
# ["income:concessions", 0, "noi", "722300", "purpose", "refinancing",
# "fees:fee-one", "0", "income:gross-income", "900000", "expenses:admin", "7500",
# "fees:fee-two", "0", "address:zip", "10019", "expenses:other", "0"]
# :each_slice(2)>:with_object({})>
enum2.to_a
#=> [[["income:concessions", 0], {}], [["noi", "722300"], {}],
# [["purpose", "refinancing"], {}], [["fees:fee-one", "0"], {}],
# [["income:gross-income", "900000"], {}], [["expenses:admin", "7500"], {}],
# [["fees:fee-two", "0"], {}], [["address:zip", "10019"], {}],
# [["expenses:other", "0"], {}]]
enum2 can be thought of as a compound enumerator (though Ruby has no such concept). The hash being generated is initially empty, as shown, but will be filled in as additional elements are generated by enum2
The first value is generated by enum2 and passed to the block, and the block values are assigned values by a process called array decomposition.
(f,v),h = enum2.next
#=> [["income:concessions", 0], {}]
f #=> "income:concessions"
v #=> 0
h #=> {}
We now perform the block calculation.
f.is_a?(String)
#=> true
k,e = f.is_a?(String) ? f.split(':') : [f,nil]
#=> ["income", "concessions"]
e.nil?
#=> false
h[k] = e.nil? ? v : (h[k] || {}).merge(e=>v)
#=> {"concessions"=>0}
h[k] equals nil if h does not have a key k. In that case (h[k] || {}) #=> {}. If h does have a key k (and h[k] in not nil).(h[k] || {}) #=> h[k].
A second value is now generated by enum2 and passed to the block.
(f,v),h = enum2.next
#=> [["noi", "722300"], {"income"=>{"concessions"=>0}}]
f #=> "noi"
v #=> "722300"
h #=> {"income"=>{"concessions"=>0}}
Notice that the hash, h, has been updated. Recall it will be returned by the block after all elements of enum2 have been generated. We now perform the block calculation.
f.is_a?(String)
#=> true
k,e = f.is_a?(String) ? f.split(':') : [f,nil]
#=> ["noi"]
e #=> nil
e.nil?
#=> true
h[k] = e.nil? ? v : (h[k] || {}).merge(e=>v)
#=> "722300"
h #=> {"income"=>{"concessions"=>0}, "noi"=>"722300"}
The remaining calculations are similar.
merge overwrites a duplicate key by default.
{ "income"=> { "concessions" => 0 } }.merge({ "income"=> { "gross-income" => "900000" } } completely overwrites the original value of "income". What you want is a recursive merge, where instead of just merging the top level hash you're merging the nested values when there's duplication.
merge takes a block where you can specify what to do in the event of duplication. From the documentation:
merge!(other_hash){|key, oldval, newval| block} → hsh
Adds the contents of other_hash to hsh. If no block is specified, entries with duplicate keys are overwritten with the values from other_hash, otherwise the value of each duplicate key is determined by calling the block with the key, its value in hsh and its value in other_hash
Using this you can define a simple recursive_merge in one line
def recursive_merge!(hash, other)
hash.merge!(other) { |_key, old_val, new_val| recursive_merge!(old_val, new_val) }
end
values.each do |row|
Hash[*row].each do |key, value|
keys = key.split(':')
if !data.dig(*keys)
hh = keys.reverse.inject(value) { |a, n| { n => a } }
a = recursive_merge!(data, hh)
end
end
end
A few more lines will give you a more robust solution, that will overwrite duplicate keys that are not hashes and even take a block just like merge
def recursive_merge!(hash, other, &block)
hash.merge!(other) do |_key, old_val, new_val|
if [old_val, new_val].all? { |v| v.is_a?(Hash) }
recursive_merge!(old_val, new_val, &block)
elsif block_given?
block.call(_key, old_val, new_val)
else
new_val
end
end
end
h1 = { a: true, b: { c: [1, 2, 3] } }
h2 = { a: false, b: { x: [3, 4, 5] } }
recursive_merge!(h1, h2) { |_k, o, _n| o } # => { a: true, b: { c: [1, 2, 3], x: [3, 4, 5] } }
Note: This method reproduces the results you would get from ActiveSupport's Hash#deep_merge if you're using Rails.
This is how I would handle this:
def new_h
Hash.new{|h,k| h[k] = new_h}
end
values.flatten.each_slice(2).each_with_object(new_h) do |(k,v),obj|
keys = k.is_a?(String) ? k.split(':') : [k]
if keys.count > 1
set_key = keys.pop
obj.merge!(keys.inject(new_h) {|memo,k1| memo[k1] = new_h})
.dig(*keys)
.merge!({set_key => v})
else
obj[k] = v
end
end
#=> {"income"=>{
"concessions"=>0,
"gross-income"=>"900000"},
"noi"=>"722300",
"purpose"=>"refinancing",
"fees"=>{
"fee-one"=>"0",
"fee-two"=>"0"},
"expenses"=>{
"admin"=>"7500",
"other"=>"0"},
"address"=>{
"zip"=>"10019"}
}
Explanation:
Define a method (new_h) for setting up a new Hash with default new_h at any level (Hash.new{|h,k| h[k] = new_h})
First flatten the Array (values.flatten)
then group each 2 elements together as sudo key value pairs (.each_slice(2))
then iterate over the pairs using an accumulator where each new element added is defaulted to a Hash (.each_with_object(new_h.call) do |(k,v),obj|)
split the sudo key on a colon (keys = k.is_a?(String) ? k.split(':') : [k])
if there is a split then create the parent key(s) (obj.merge!(keys.inject(new_h.call) {|memo,k1| memo[k1] = new_h.call}))
merge the last child key equal to the value (obj.dig(*keys.merge!({set_key => v}))
other wise set the single key equal to the value (obj[k] = v)
This has infinite depth as long as the depth chain is not broken say [["income:concessions:other",12],["income:concessions", 0]] in this case the latter value will take precedence (Note: this applies to all the answers in one way or anther e.g. the accepted answer the former wins but a value is still lost dues to inaccurate data structure)
repl.it Example
Given the following hash structure...
{
a: nil,
b: [],
c: {c1: {c2: nil}},
d: [{d1: "Value!"}],
e: "Value!",
f: {f1: {f2: nil, f3: "Value!"}}
}
I'd like to be able to return...
{
d: [{d1: "Value!"}],
e: "Value!",
f: {f1: {f3: "Value!"}}
}
So the rules would be
1) Remove any key that points to a nil, {}, or [] value
2) Remove any key that leads to value which points to an empty value (example c: from the original hash)
3) Preserve the outer key if one or more inner keys point to a non empty value, but remove inner keys that point to an empty value. (see f: and notice that f2: is removed)
Any help would be appreciated!
You could have some fun with monkey-patching the core classes involved:
class Object
def crush
self
end
end
class Array
def crush
r = map(&:crush).compact
r.empty? ? nil : r
end
end
class Hash
def crush
r = each_with_object({ }) do |(k, v), h|
if (_v = v.crush)
h[k] = _v
end
end
r.empty? ? nil : r
end
end
It's an unusual thing to want to do, but if you do need it done writing a method like crush might help.
This should be a one pass operation that works with nested arrays and hashes:
def crush(thing)
if thing.is_a?(Array)
thing.each_with_object([]) do |v, a|
v = crush(v)
a << v unless [nil, [], {}].include?(v)
end
elsif thing.is_a?(Hash)
thing.each_with_object({}) do |(k,v), h|
v = crush(v)
h[k] = v unless [nil, [], {}].include?(v)
end
else
thing
end
end
def deep_compact(hash)
res_hash = hash.map do |key, value|
value = deep_compact(value) if value.is_a?(Hash)
value = nil if [{}, []].include?(value)
[key, value]
end
res_hash.to_h.compact
end
I would like to compare an Array to an element and extract those data in the another Array
Here is an example of data i'm working with:
Array = [{:id=>3, :keyword=>"happy", :Date=>"01/02/2016"},
{:id=>4, :keyword=>"happy", :Date=>"01/02/2016"} ... ]
for example i want the first keyword happy to search the same array ,extract if there's any similar words and put them inside another array here is what i'm looking for an end result:
Results = [{:keyword=>happy, :match =>{
{:id=>3, :keyword=>"happy", :Date=>"01/02/2016"}... }]
Here is the first part of the code :
def relationship(file)
data = open_data(file)
parsed = JSON.parse(data)
keywords = []
i = 0
parsed.each do |word|
keywords << { id: i += 1 , keyword: word['keyword'].downcase, Date: word['Date'] }
end
end
def search_keyword(keyword)
hash = [
{:id=>1, :keyword=>"happy", :Date=>"01/02/2015"},
{:id=>2, :keyword=>"sad", :Date=>"01/02/2016"},
{:id=>3, :keyword=>"fine", :Date=>"01/02/2017"},
{:id=>4, :keyword=>"happy", :Date=>"01/02/2018"}
]
keywords = []
hash.each do |key|
if key[:keyword] == keyword
keywords << key
end
end
keywords
#{:keyword=> keyword, :match=> keywords}
end
search_keyword('fine')
#search_keyword('sad')
You could group the match elements by key (:match) then get the result with a single hash lookup.
Here's another idea that could help you with your situation using enumerable and index:
array to be search:
array = [
{:id=>3, :keyword=>"happy", :Date=>"01/02/2016"},
{:id=>4, :keyword=>"happy", :Date=>"01/02/2016"},
{:id=>1, :keyword=>"happy", :Date=>"01/02/2015"},
{:id=>2, :keyword=>"sad", :Date=>"01/02/2016"},
{:id=>30, :keyword=>"fine", :Date=>"01/02/2017"},
{:id=>41, :keyword=>"happy", :Date=>"01/02/2018"}
]
method search:
store all element matching the term in the array.
def search(term, array)
array = []
array << {keyword: "#{term}", match: []}
arr.select { |element| array.first[:match] << element if element[:keyword].index(term) }
array
end
Testing:
p search('sa', array)
# => [{:keyword=>"sa", :match=>[{:id=>2, :keyword=>"sad", :Date=>"01/02/2016"}, {:id=>21, :keyword=>"sad", :Date=>"01/02/2016"}]}]
hope that will get you goin!
I want to create a hash with an index that comes from an array.
ary = ["a", "b", "c"]
h = Hash.new(ary.each{|a| h[a] = 0})
My goal is to start with a hash like this:
h = {"a"=>0, "b"=>0, "c"=>0}
so that later when the hash has changed I can reset it with h.default
Unfortunately the way I'm setting up the hash is not working... any ideas?
You should instantiate your hash h first, and then fill it with the contents of the array:
h = {}
ary = ["a", "b", "c"]
ary.each{|a| h[a] = 0}
Use the default value feature for the hash
h = Hash.new(0)
h["a"] # => 0
In this approach, the key is not set.
h.key?("a") # => false
Other approach is to set the missing key when accessed.
h = Hash.new {|h, k| h[k] = 0}
h["a"] # => 0
h.key?("a") # => true
Even in this approach, the operations like key? will fail if you haven't accessed the key before.
h.key?("b") # => false
h["b"] # => 0
h.key?("b") # => true
You can always resort to brute force, which has the least boundary conditions.
h = Hash.new.tap {|h| ["a", "b", "c"].each{|k| h[k] = 0}}
h.key?("b") # => true
h["b"] # => 0
You can do it like this where you expand a list into zero-initialized values:
list = %w[ a b c ]
hash = Hash[list.collect { |i| [ i, 0 ] }]
You can also make a Hash that simply has a default value of 0 for any given key:
hash = Hash.new { |h, k| h[k] = 0 }
Any new key referenced will be pre-initialized to the default value and this will avoid having to initialize the whole hash.
This may not be the most efficient way, but I always appreciate one-liners that reveal a little more about Ruby's versatility:
h = Hash[['a', 'b', 'c'].collect { |v| [v, 0] }]
Or another one-liner that does the same thing:
h = ['a', 'b', 'c'].inject({}) {|h, v| h[v] = 0; h }
By the way, from a performance standpoint, the one-liners run about 80% of the speed of:
h = {}
ary = ['a','b','c']
ary.each { |a| h[a]=0 }
Rails 6 added index_with on Enumerable module. This will help in creating a hash from an enumerator with default or fetched values.
ary = %w[a b c]
hash = ary.index_with(0) # => {"a"=>0, "b"=>0, "c"=>0}
Another option is to use the Enum#inject method which I'm a fan of for its cleanliness. I haven't benchmarked it compared to the other options though.
h = ary.inject({}) {|hash, key| hash[key] = 0; hash}
Alternate way of having a hash with the keys actually added
Hash[[:a, :b, :c].zip([])] # => {:a=>nil, :b=>nil, :c=>nil}
Hash[[:a, :b, :c].zip(Array.new(3, 0))] # => {:a=>0, :b=>0, :c=>0}