# Histogram A Histogram is just that, more precisely, it is:
    template <typename T>
    class Histogram;
It can be used to count how many elements of type T, from a source of input, fall into certain bins. ## Interface Iterators providing access to the elements of a Histogram are all read-only. Dereferencing an iterator yields a type 'const std::pair<unsigned int, unsigned int>' where 'first' is the number of the bin, and 'second' in the number of times an element fell into the bin.
    value_type
| The type of object that are being counted.
    const_iterator
| A read-only iterator that passes over all non-empty bins.
    const_reverse_iterator
| A read-only iterator that passes over all non-empty bins.
    Histogram(const unsigned nrBins =
    			std::numeric_limits<unsigned>::max(),
    	  const value_type minValue = value_type(0),
    	  const value_type maxValue =
    			std::numeric_limits<value_type>::max())
| Default constructor, by default, the number of bins is std::numeric_limits<unsigned>::max(), minValue is zero and maxValue is std::numeric_limits<unsigned>::max().
    template <typename InputIterator>
    Histogram(const InputIterator first, const InputIterator last,
    	  const unsigned nrBins,
    	  const value_type minValue = value_type(0),
    	  const value_type maxValue =
    			 std::numeric_limits<value_type>::max())
| Constructs a Histogram, and fills it based on the input given by InputIterator first and last.
    unsigned size() const
| Returns the number of non-empty bins.
    unsigned maxSize() const
| Returns the maximum number of non-empty bins, i.e. the largest value that size() can return.
    unsigned elements() const
| The number of elements that has been inserted, or the sum of all bins.
    const_iterator
    atLeastPercentGreater(const double percentElements) const
| Given a number between 0.0 and 1.0, returns an iterator to the lowest bin in the histogram such that dataPercent percent of the data is in bins lower than the returned element.
    const_iterator atLeastGreater(const unsigned elements) const
| Returns an iterator to a bin such that the sum of the previous bins at least equals elements.
    const_reverse_iterator
    atMostPercentGreater(const double percentElements) const
| Given a number between 0.0 and 1.0, returns an iterator to the highest bin in the histogram such that percentElements percent of the data is in bins higher than the returned element.
    const_reverse_iterator
    atMostGreater(const unsigned elements) const
| Returns an iterator to a bin such that there are at least elements in the bins higher than the returned bin.
    double binSize() const
| Return the 'width' of one bin.
    void clear()
| Remove all data from the Histogram.
    void insert(const value_type &value)
| Insert value.
    template <typename InputIterator>
    void insert(const InputIterator first, const InputIterator last)
| Insert all elements in the range first to last.
    template <typename InputIterator, class UnaryFunction>
    void insert(const InputIterator first, const InputIterator last,
    	    UnaryFunction op)
| For all elements in the range first to last: apply op, then insert.
    float operator()(const unsigned bin) const
| The fraction of the all the elements that are in bin.
    const_iterator begin()
| A const_iterator: begin.
    const_iterator end()
| A const_iterator: end.
    const_reverse_iterator rbegin()
| A const_reverse-iterator: begin.
    const_reverse_iterator rend()
| A const_reverse-iterator: end.
    double avg() const
| The average value of the non-empty bins.
    Histogram &operator+=(const Histogram &rhs)
| Merge the results in another Histogram.