Using JPythonMethod's histogram function

May, 2001

Introduction

The hist() function in JPythonMethods provides the mechanism to create a Histogram VisAD Data object. This consists of bins of counts of values. You may use this method directly, or for simple "bar graph" type displays, you can use the graph.histogram() function.

Here are the signatures for the hist() funciton:

hist(field, int[] ranges)
Return a Data object that contains counts for the indicated range components in 20 equally-spaced bins. You may specify more than on range component, in order to get a multi-dimensional histogram.
hist(field, int[] ranges, int[] sizes)
Return a Data object where you specify the ranges and the bin sizes for each.
hist(field, set)
Return a Data object where the dimension and bin sampling are defined by the set

Here's an example:

a = load("../data/mcidas/AREA0008")
h = hist(a, [0,2], [20,40])
plot(h)

Produces this display:

Picture of 2-D histogram

which maps the count of brightness values of channel 0 into 20 equally-spaced bins, the count of brightness for channel 2 into 40 bins.

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