I have a concept called snapshot which basically stores a snapshot of how data looked at a certain period of time. What I'm building is a method that loops through the snapshots for each events, and builds a small hash outlining the ownership over time for a given shareholder.
def fetch_ownership_over_time(shareholder, captable)
#shareholder = Shareholder.find(shareholder.id)
#captable = Captable.find(captable.id)
#company = #captable.company.id
#ownership_over_time = []
#captable.events.collect(&:snapshot).each do |snapshot|
parsed_snapshot = JSON.parse(snapshot)
#ownership_over_time.push(parsed_snapshot["event"]["name"])
#ownership_over_time.push(parsed_snapshot["event"]["date"])
parsed_snapshot["shareholders"].each do |shareholder|
if shareholder["id"] == #shareholder.id
#ownership_over_time.push(shareholder["ownership_percentage"])
end
end
end
return #ownership_over_time
end
I then call this method in my view which successfully retrieves the correct values however they are not structured in any way:
["Event 1 ", "2018-11-19", "0.666666666666667", "Event 2 ", "2018-11-19", "0.333333333333333", "4th event ", "2018-11-19", "0.315789473684211"]
What I'd like to do now though is construct my hash so that each separate snapshot event contains a name, date and ownership_percentage.
Perhaps something like this:
ownership_over_time = [
{
event_name = "Event 1" #parsed_snapshot["event"]["name"]
event_date = "20180202" #parsed_snapshot["event"]["date"]
ownership_percentage = 0.37 #shareholder["ownership_percentage"]
},
{
event_name = "Event 2" #parsed_snapshot["event"]["name"]
event_date = "20180501" #parsed_snapshot["event"]["date"]
ownership_percentage = 0.60 #shareholder["ownership_percentage"]
}
]
My challenge though is that the ["event"]["name"] an ["event"]["date"] attributes I need to fetch when looping over my snapshots i.e. the first loop (.each do |snapshot|) whereas I get my ownership_percentage when looping over shareholders - the second loop (.each do |shareholder|).
So my question is - how can I build this hash in "two" places so I can return the hash with the 3 attributes?
Appreciative of guidance/help - thank you!
You have to create a new hash for the object and append that hash to the array of objects you are creating.
def fetch_ownership_over_time(shareholder, captable)
#shareholder = Shareholder.find(shareholder.id)
#captable = Captable.find(captable.id)
#company = #captable.company.id
#ownership_over_time = []
#captable.events.collect(&:snapshot).each do |snapshot|
parsed_snapshot = JSON.parse(snapshot)
shareholder = parsed_snapshot['shareholders'].select { |s| s['id'] == #shareholder.id }.first
local_snapshot = {
'event_name' => parsed_snapshot['event']['name'],
'event_date' => parsed_snapshot['event']['date'],
'ownership_percentage' => shareholder.try(:[], "ownership_percentage") || 0
}
#ownership_over_time.push local_snapshot
end
return #ownership_over_time
end
Notice that I changed your second loop to a select. As you currently have it, you risk on pushing two percentages if the id is found twice.
EDIT:
Added functionality to use a default value if no shareholder is found.
Related
So, I have an after_save hook on review model which calls calculate_specific_rating function of product model. The function goes like this:
def calculate_specific_rating
ratings = reviews.reload.all.pluck(:rating)
specific_rating = Hash.new(0)
ratings.each { |rating| specific_rating[rating] += 1 }
self.specific_rating = specific_rating
save
end
Right now, it returns
specific_rating => {
"2"=> 3, "4"=> 1
}
I want it to return like:
specific_rating => {
"1"=> 0, "2"=>3, "3"=>0, "4"=>1, "5"=>0
}
Also, is it okay to initialize a new hash everytime a review is saved? I want some alternative. Thanks
You can create a range from 1 until the maximum value in ratings plus 1 and start iterating through it, yielding an array where the first element is the current one, and the second element is the total of times the current element is present in ratings. After everything the result is converted to a hash:
self.specific_rating = (1..ratings.max + 1).to_h { |e| [e.to_s, ratings.count(e)] }
save
You could also do something like this -
def calculate_specific_rating
ratings = [1,2,3,4,5]
existing_ratings = reviews.group_by(&:rating).map{|k,v| [k, v.count]}.to_h
Hash[(ratings - existing_ratings.keys).map {|x| [x, 0]}].merge(existing_ratings)
end
which gives
{3=>0, 4=>0, 5=>0, 2=>3, 1=>1}
I want to make an array of hashes. But the problem is after first iteration when code goes to next line then it directly replaces the content of array.
#item_name =[]
item = {}
#invoiceinfo.each do |invoice|
item[:name] = Invoiceinfo.find(#invoiceinfo.id).item.name
item[:desc] = Invoiceinfo.find(#invoiceinfo.id).desc
item[:unit_price] = Invoiceinfo.find(#invoiceinfo.id).unit_price
byebug
#item_name.push (item)
end
This is what i am getting
after first iteration suppose i have this data
#item_name = [{:name=>"usman", :desc=>"sample ", :unit_price=>100}]
As soon as next line is executed it directly changes #item_name(name variable)
After executing item[:name] = Invoiceinfo.find(#invoiceinfo.id).item.name
the content of the #item_name is changed
#item_name = [{:name=>"next_name", :desc=>"sample ", :unit_price=>100}]
Any help would be appreciated.
Thannks
Try something like this
#item_name = []
#invoiceinfo.each do |invoice|
invoice_info = Invoiceinfo.find(#invoiceinfo.id)
item = {}
item[:name] = invoice_info.item.name
item[:desc] = invoice_info.desc
item[:unit_price] = invoice_info.unit_price
#item_name.push(item)
end
If you consider using ruby paradigms and best practices in ruby code, this mistake won’t happen in the future.
#item_name = #invoiceinfo.each_with_object([]) do |invoice, acc|
invoice_info = Invoiceinfo.find(#invoiceinfo.id)
acc.push(
name: invoice_info.item.name,
desc: invoice_info.desc
unit_price: invoice_info.unit_price
)
end
I have a array which is inside a hash. I want know the result of the student (pass/fail) using the following array. First I have to match them with particular standard and compare their marks with the hash pass and fails. And I want to get the key pass or fail based on their mark. How to achieve this using Ruby?
array = [
{
:standard =>1
:pass=>{:tamil=>30,:eng=>25,:math=>35},
:fail=>{:tamil=>10,:eng=>15,:maths=>20}
},
{
:standard =>2,
:pass=>{:tamil=>40,:eng=>35,:math=>45},
:fail=>{:tamil=>20,:eng=>25,:maths=>30}
}
]
#student is assumed to be defined
standard = array.select {|standard| standard[:standard] == #student.standard}
eng_pass = #student.eng_mark >= standard[:pass][:eng]
eng_fail = #student.eng_mark <= standard[:fail][:eng]
return [eng_pass, eng_fail, whatever_else_you_want]
So on and forth for various topics.
The syntax in reading values from this structure is something like:
array[0][:pass][:eng]
and accordingly you can do the comparison as usual in batch:
for i in 0..#students_array.length
num = # student's score
standard = # something like array[0][:pass][:eng]
if num > standard
# something like 'put "You passed!"'
end
end
I have this method
def gen_events(score)
events = location.events
(1..rand(5..7)).each do |n|
random = rand(0.139..1).round(3)
rarity = Character.get_rarity(random)
event = events.where(rarity: rarity).shuffle.shift #<-- HERE
self.events << event
end
end
Currently, the shift method only grabs the first element, but doesn't remove it, how can I go about making it so that it does both?
This is not an array: events.where(rarity: rarity), this is an ActiveRecord scope, you can't remove things from it without destroying and erasing them from database. Instead, you should keep an array of object you already found, and use it to filter future results:
def gen_events(score)
events = location.events
new_events = []
(1..rand(5..7)).each do |n|
random = rand(0.139..1).round(3)
rarity = Character.get_rarity(random)
event = events.where(rarity: rarity).where.not(id: new_events.map(&:id).sample
new_events << event
end
self.events << new_events
end
I have this code here and it works but there has to be a better way.....i need two arrays that look like this
[
{
"Vector Arena - Auckland Central, New Zealand" => {
"2010-10-10" => [
"Enter Sandman",
"Unforgiven",
"And justice for all"
]
}
},
{
"Brisbane Entertainment Centre - Brisbane Qld, Austr..." => {
"2010-10-11" => [
"Enter Sandman"
]
}
}
]
one for the past and one for the upcoming...the problem i have is i am repeating myself and though it works i want to clean it up ...here is my data
..
Try this:
h = Hash.new {|h1, k1| h1[k1] = Hash.new{|h2, k2| h2[k2] = []}}
result, today = [ h, h.dup], Date.today
Request.find_all_by_artist("Metallica",
:select => "DISTINCT venue, showdate, LOWER(song) AS song"
).each do |req|
idx = req.showdate < today ? 0 : 1
result[idx][req.venue][req.showdate] << req.song.titlecase
end
Note 1
In the first line I am initializing an hash of hashes. The outer hash creates the inner hash when a non existent key is accessed. An excerpt from Ruby Hash documentation:
If this hash is subsequently accessed by a key that doesn‘t correspond to a hash
entry, the block will be called with the hash object and the key, and should
return the default value. It is the block‘s responsibility to store the value in
the hash if required.
The inner hash creates and empty array when the non existent date is accessed.
E.g: Construct an hash containing of content as values and date as keys:
Without a default block:
h = {}
list.each do |data|
h[data.date] = [] unless h[data.date]
h[data.date] << data.content
end
With a default block
h = Hash.new{|h, k| h[k] = []}
list.each do |data|
h[data.date] << data.content
end
Second line simply creates an array with two items to hold the past and future data. Since both past and the present stores the data as Hash of Hash of Array, I simply duplicate the value.
Second line can also be written as
result = [ h, h.dup]
today = Date.today