DZone Snippets: range code

Ping a range of IP addresses

jrobertson (James Robertson) — Tue, 11 Mar 2008 09:06:19 GMT



(1..254).each {|i| puts ": found 192.168.1.#{i}" if  `ping 192.168.1.#{i} -c 1 -w 1`.match(/ttl/) }

Convert Ruby Array to Ranges

bsiggelkow (Bill Siggelkow) — Fri, 19 Oct 2007 13:03:58 GMT

# Array#to_ranges
# Converts an array of values (which must respond to #succ) to an array of ranges. For example,
# [3,4,5,1,6,9,8].to_ranges => [1,3..6,8..9]



class Array

  def to_ranges

    array = self.compact.uniq.sort

    ranges = []

    if !array.empty?

      # Initialize the left and right endpoints of the range

      left, right = self.first, nil

      array.each do |obj|

        # If the right endpoint is set and obj is not equal to right's successor 

        # then we need to create a range.

        if right && obj != right.succ

          ranges << Range.new(left,right)

          left = obj

        end

        right = obj

      end

      ranges << Range.new(left,right)

    end

    ranges

  end

end

Collapse ranges in arrays

sporkyy (Todd Sayre) — Sun, 03 Jun 2007 17:59:53 GMT

Takes an Array and turns consecutive integers into Range objects.



class Array

    def collapse_ranges

        return self if self.length <= 2

        self.uniq!

        self.sort! rescue nil

        temp_array, return_array = [], []

        self.each_with_index do |item, i|

            if item.respond_to?(:next)

                temp_array.push item

                if item.next != self[i + 1]

                    return_array.concat 3 <= temp_array.length ?

                        [temp_array.first..temp_array.last] :

                         temp_array

                    temp_array.clear

                end

            else

                return_array.concat 3 <= temp_array.length ?

                    [temp_array.first..temp_array.last] :

                     temp_array

                temp_array.clear

                return_array.push item

            end

        end

        return return_array

    end

end



>> [1, 3, 4, 5, 7, 8].collapse_ranges.join(', ')

=> 1, 3..5, 7, 8

>> %w(a c d e g i j).collapse_ranges.join(', ')

=> a, c..e, g, i, j

>> [1, 2.5, 3, 4, 5].collapse_ranges.join(', ')

=> 1, 2.5, 3..5

>> [1, 2, 3, 4, {:test => 'value'}, 5].collapse_ranges.join(', ')

=> 1..4, testvalue, 5

Ruby: make ranges always include the last value

technodolt (Luke Ivers) — Thu, 12 Apr 2007 17:36:56 GMT

So, in conjunction with other snipped about setting up intervals on Time, this can be added to Range to make sure it always includes the last value, even if the interval doesn't directly land you on the end value



class Range

  def each(options = {}, &block)

    val = self.begin

    while val < self.end

      yield val

      val = val.succ

    end

    yield self.end if self.end == val || options[:always_include_last]

  end

end

Find missing array items

sporkyy (Todd Sayre) — Thu, 18 Jan 2007 08:15:54 GMT

This works fine for integers and letters. It should work for anything though, so long as Ruby can form an range from the first and last array items.



class Array

    def missing_items

        return [] if self.length <= 1

        self.uniq!

        self.sort! rescue nil

        begin

            (self.first..self.last).to_a - self

        rescue

            []

        end

    end

end



>> [1, 3, 4, 10].missing_items.join(', ')

=> 2, 5, 6, 7, 8, 9

>> [1, 2, 7, 7.5, 8.2].missing_items.join(', ')

=> 3, 4, 5, 6, 8

>> %w(a b c f g j).missing_items.join(', ')

=> d, e, h, i

>> [2.5, {:test => 'value'}].missing_items.join(', ')

=>

A range function with float increment

korakot (Korakot Chaovavanich) — Sat, 18 Feb 2006 20:45:03 GMT

Taken from Edvard Majakari's comment in this recipe.



def arange(start, stop=None, step=None):

    if stop is None:

        stop = float(start)

        start = 0.0

    if step is None:

        step = 1.0

    cur = float(start)

    while cur < stop:

        yield cur

        cur += step

For python 2.2 (e.g. pys60) you need to do a "from __future__ import generators" first.
To get the list from the generator, use list(arange(...))