Histogram in Machine Learning

Plotting histograms, of frequency histograms, is a graphical method for summarizing the distribution of a given attribute. A histogram for an attribute A partitions the data distribution of  A into disjoint subsets, or buckets. Typically, the width of each bucket is uniform. Each bucket is represented by a rectangle whose height is equal to the count or relative frequency of the values at the bucket. If A is categoric, such as an automobile model or item_type, then one rectangle is drawn for each known value of A, and the resulting graph is more commonly referred to as a bar chart. If A is numeric, the term histogram is preferred. In an equal-width histogram, each bucket represents an equal-width range of numerical attribute A.

Fig. snows a histogram for the data set of table 1.6, where buckets are defined by equal-width ranges representing $20 increments and the frequency is the count of items sold.

                                                                                A set of Unit Price Data for Items Sold at a Branch of AII Electronics