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module CoreExt; module Array
# Check if all array members are instances of given class(es).
#
# @return [Boolean]
# @param [Array, Class] klasses_allowed Array of classes, or a single class
# @note Returns <tt>true</tt> if the array is empty.
def is_array_of?(klasses_allowed)
if klasses_allowed.kind_of? Array
fail ArgumentError, "Array of Classes expected. Some members are not instances of Class." \
unless klasses_allowed.is_array_of?(Class)
elsif klasses_allowed.kind_of? Class
klasses_allowed = [klasses_allowed]
else
fail ArgumentError, "Class or array of classes expected, #{klasses_allowed.class.name} given"
end
return true if self.empty?
self.map(&:class).uniq.reject{ |klass| klasses_allowed.include?(klass) }.empty?
end
# @note Sums array members.
#
# @return [nil] If source array contains non-numeric values.
# @return [Fixnum, Integer, Float]
def sum
return nil unless self.is_array_of? [Integer, Float, Fixnum]
self.inject(0) { |sum, value| sum + value }
end
# Boil down values proportionally, to make their sum equal to <tt>target_sum</tt>.
#
# @param [Fixnum] target_sum
# @return [Array] Array of pairs [old value, new_value].
def reduce_to_sum(target_sum)
current_sum = self.sum
gap = current_sum - target_sum
if gap < 0
return nil
elsif gap == 0
return self.collect { |value| [value, value] }
else
reduced = 0
result = self.collect do |value|
x = (gap * value) / current_sum # Floats round here
reduced += x
[value, value - x]
end
# Second pass, as target sum is not reached yet due to rounding of floats
(gap - reduced).times { |i| result[i][1] -= 1 }
result
end
end
end; end
if defined? Array
Array.class_eval do
include CoreExt::Array
end
end
https://github.com/gorodulin/assemblr/blob/master/lib/core_ext/array.rb
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