CODEWITHSUNDEEP
rubyarrays
user419017
user419017

Reputation:

Get max consecutive occurrences of value in array

Is there a more elegant way to achieve this below:

Input:

array = [1, 1, 1, 0, 0, 1, 1, 1, 1, 0]

Output:

4

My algo:

streak = 0
max_streak = 0

arr.each do |n|
  if n == 1
    streak += 1
  else
    max_streak = streak if streak > max_streak
    streak = 0
  end
end

puts max_streak

Upvotes: 5

Views: 1930

Answers (4)

Sid
Sid

Reputation: 2943

Edit: Another way to do this (that is less generic than Stefan's answer since you would have to flatten and split again if there was another number other than 0 and 1 in there, but easier to use in this case):

array.split(0).max.count

You can use:

array.chunk { |n| n }.select { |a| a.include?(1) }.map { |y, ys| ys.count}.max

ref: Count sequential occurrences of element in ruby array

Upvotes: 6

Cristian Lupascu
Cristian Lupascu

Reputation: 40526

You can use Enumerable#chunk:

p array.chunk{|x| x}.select{|x, xs| x == 1}.map{|x, xs| xs.size }.max

This is more concise, but if performance was important, I'd use your approach.

Edit: If you're in Ruby 2.2.2, you can also use the new Enumerable#slice_when method (assuming your input array consists of only 0s and 1s):

array.slice_when{|x,y| x < y }.map{|slice| slice.count 1 }.max

Upvotes: 5

Avdept
Avdept

Reputation: 2289

How about

array = [1, 1, 1, 0, 0, 1, 1, 1, 1, 0]

array.split(0).group_by(&:size).max.first #=> 4

The only bad thing - split(0)

Note: This only works with rails's ActiveSupport(extends Array with #split)

For ruby-only implementation

array.join.split("0").group_by(&:size).max.first #=> 4

Upvotes: 0

Stefan
Stefan

Reputation: 114168

Similar to w0lf's answer, but skipping elements by returning nil from chunk:

array.chunk { |x| x == 1 || nil }.map { |_, x| x.size }.max

Upvotes: 6

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