lighttroupe/luz

class Array
    def collect_with_index
        a = []
        self.each_with_index { |obj, index| a << yield(obj, index) }
        a
    end

    def collect_non_nil
        a = []
        self.each { |obj| value = yield obj ; a << value unless value.nil? }
        a
    end

    def append_or_replace(rhs)
        each_with_index { |obj, i|
            if yield(obj, rhs)
                self[i] = rhs  # replace
                return
            end
        }
        self << rhs
    end

    def multiply_each(value)
        each_index { |i| self[i] *= value }
    end

    # returns the average change between array elements        NOTE: requires at least two elements
    def delta_min_max_avg
        min, max, total = nil, nil, 0.0

        for i in 0..size-2
            difference = self[i + 1] - self[i]
            min = difference if (min.nil? || difference < min)
            max = difference if (max.nil? || difference > max)
            total += difference
        end
        [min, max, total / (size - 1)]
    end

    #
    # set min/max/avg
    #
    def sum
        total = self.first        # avoid caring about type
        each_with_index { |v, i| total += v if (v && i > 0) }
        total
    end

    def average
        total, count = 0.0, 0
        each { |v|
            if v
                total += v
                count += 1
            end
        }
        return nil if size == 0
        total / count
    end

    def minimum
        min = nil
        each { |v| min = v if (min.nil? || v < min) }
        min
    end

    def maximum
        max = nil
        each { |v| max = v if (max.nil? || v > max) }
        max
    end
end