Count same values on array using each Ruby Rails

Question

I execute the query in the bank by the controller and I receive the data in the var when executing each on top of the var returns me an array, I wanted to count how many times the same parameter is repeated to create a counter could help me follow my code.

Rails 3.2, ruby 2.3

results os my query.. from postgresql

#<tickets title: "any text any first register ", updated_at: "2018-01-30 18:38:58", company: 89869> 

#<tickets title: "any text any second register ", updated_at: "2018-06-25 20:18:20", company: 99991>

I want to count how many times the same date is repeated regardless of the time to count the number of times that displays the same date.

You need to count a specific date or how many times each date repeated? — Yakov
– Yakov, Commented Feb 19, 2020 at 18:54

max pleaner · Accepted Answer · 2020-02-19 18:53:38Z

2

My usual approach is to use group_by and transform_values.

counts_by_date = tickets.group_by do |ticket|
  ticket.updated.at.strftime("%Y/%m/%d") # get Year/Month/Day as string
end.transform_values(&:count)

With Ruby 2.7 we get tally which is slightly shorter:

counts_by_date = tickets.map do |ticket|
  ticket.updated.at.strftime("%Y/%m/%d") # get Year/Month/Day as string
end.tally

answered Feb 19, 2020 at 18:53

max pleaner

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5 Comments

codevb Over a year ago

undefined method `transform_values' for #<Hash:0x0000561021013038>

Cary Swoveland Over a year ago

codevb, Hash#transform_values was introduced in Ruby v2.4. Does that explain your finding?

codevb Over a year ago

i want, count same date time was returning from postgresql using each.

Dan Over a year ago

Hmm, I've been doing this for years and have never seen the syntax where you chain a method off the end statement. I guess I've done similar things using the single line method { |x| something }.something_else. I guess they're the same under the hood?

max pleaner Over a year ago

@Dan Yeah it is not the prettiest thing, but I prefer to be consistent and always use do ... end for multiline blocks anyway

Yakov · Accepted Answer · 2020-02-19 19:40:20Z

1

For a specific value you can use count method:

date = Date.today # Put your date here
tickets.count { |ticket| ticket.updated_at.to_date == date }

UPD

Group tickets by date and take the result from the hash. I am not sure if it works in Rails 3.2

date = Date.today # Put your date here
Ticket.group('date(updated_at)').size[date]

edited Feb 19, 2020 at 19:40

answered Feb 19, 2020 at 19:08

Yakov

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5 Comments

Cary Swoveland Over a year ago

That means you would need to enumerate the array for each of its elements, which is extremely inefficient.

Yakov Over a year ago

But how you count suitable elements without enumerating them all? Only if we group tickets by date on DB level but it is a different approach.

codevb Over a year ago

tested, it worked fine is showing the count of equal dates after reading 20 records thankyou !!

Cary Swoveland Over a year ago

Compare what you have with @max's solution (especially the use of Enumerable#tally). Both of the calculations he gives require a single pass through the array to obtain the counts for all unique elements in the array. You are making a pass through the array for each unique element in the array.

Yakov Over a year ago

But this is the point. The question is how to count how many times the certain date is present. count method is made for this purpose, use group_by is overcomplication.

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