# Module Scientific.Statistics.Histogram

## Class Histogram: Histogram in one variable

Constructor: Histogram(data, bins, range=None)

data

  a sequence of data points

bins

  the number of bins into which the data is to be sorted

range

  a tuple of two values, specifying the lower and the upper end of the interval spanned by the bins. Any data point outside this interval will be ignored. If no range is given, the smallest and largest data values are used to define the interval.

The bin index and the number of points in a bin can be obtained by indexing the histogram with the bin number. Application of len() yields the number of bins. A histogram thus behaves like a sequence of bin index - bin count pairs.

Methods:

- addData(data)

  Add the values in data (a sequence of numbers) to the originally supplied data. Note that this does not affect the default range of the histogram, which is fixed when the histogram is created.

- normalize(norm=`1.0`)

  Scales all counts by the same factor such that their sum is norm.

- normalizeArea(norm=`1.0`)

  Scales all counts by the same factor such that the area under the histogram is norm.

## Class WeightedHistogram: Weighted histogram in one variable

Constructor: WeightedHistogram(data, weights, bins, range=None)

data

  a sequence of data points

weights

  a sequence of weights, same length as data

bins

  the number of bins into which the data is to be sorted

range

  a tuple of two values, specifying the lower and the upper end of the interval spanned by the bins. Any data point outside this interval will be ignored. If no range is given, the smallest and largest data values are used to define the interval.

In a weighted histogram, each point has a specific weight. If all weights are one, the result is equivalent to a standard histogram. The bin index and the number of points in a bin can be obtained by indexing the histogram with the bin number. Application of len() yields the number of bins. A histogram thus behaves like a sequence of bin index - bin count pairs.

Methods:

- addData(data, weights)

  Add the values in data (a sequence of numbers) with the given weights to the originally supplied data. Note that this does not affect the default range of the histogram, which is fixed when the histogram is created.