The Shannon Entropy of a Histogram

The histogram is a key method for visualizing data and estimating the underlying probability distribution. Incorrect conclusions about the data result from over or under-binning. A new method based on the Shannon entropy of the histogram uses a simple formula based on the differential entropy estimated from nearest-neighbour distances. Links are made between the new method and other algorithms such as Scott's formula, and cost and risk function methods. A parameter is found that predicts over and under-binning, which can be estimated for any histogram. The new algorithm is shown to be robust by application to real data.