CODEWITHSUNDEEP
ruby
wiredin
wiredin

Reputation: 269

Best way to initialize a temp variable that is used in a loop

What is the best way to initialize a temp variable that is used in a loop to keep track of a previous value?

Here is the example of how I would do it but I feel there is a cleaner way. I only want to print the show date if the previous show was on a different day

temp_show_date = ""
shows.each do |show|
  if temp_show_date != show.date
    puts show.date
  end
  puts show.name
  temp_show_date = show.date
 end

Upvotes: 4

Views: 368

Answers (5)

sawa
sawa

Reputation: 168199

shows.each_cons(2) do |s1, s2|
  puts s2.date unless s1.date == s2.date
  puts s2.name
end

To print the first one, you can prepare a dummy show dummy, whose date is empty, and use [dummy, *shows] instead of shows.

Upvotes: 0

fotanus
fotanus

Reputation: 20116

I could write your snipped differently, but answering your question

best way to initialize a temp variable

would be the each_with_object

shows.each_with_object("") do |temp_show_date, show|
  if temp_show_date != show.date
    puts show.date
  end
  puts show.name
  temp_show_date = show.date
 end

Upvotes: 2

matt
matt

Reputation: 535566

This shows one approach (using a simple array; you will have to adapt to your particular object type):

arr = [1,1,2,1,2,2,3,1]
arr.each_cons(2) do |a,b|
  puts b unless b == a
end

Upvotes: 1

Chris
Chris

Reputation: 12181

So you want to iterate of each group of two consecutive elements. Try Enumerable#each_cons

shows.each_cons(2) do |first_show, second_show|
  if first_show.date != second_show.date
    puts "these two aren't on the same day!"
  end
end

Upvotes: 1

Zach Kemp
Zach Kemp

Reputation: 11904

I would probably restructure the data using group_by so it more or less matches the desired output. Then you can output the date once, as it becomes the key in a hash, followed by the array of shows for that date:

shows.group_by(&:date).each do |date, date_shows|
  puts date
  puts date_shows
end

(I'm using IRB's default behavior for supplying arrays as arguments to puts, wherein each element is printed on a new line. You can loop through that array if you need to do something else with them).

Upvotes: 5

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