nclass: Compute the Number of Classes for a Histogram

Description

Compute the number of classes for a histogram.

Usage

nclass.Sturges(x)
nclass.scott(x)
nclass.FD(x)

Arguments

A data vector.

Value

The suggested number of classes.

Details

nclass.Sturges uses Sturges' formula, implicitly basing bin sizes on the range of the data. nclass.scott uses Scott's choice for a normal distribution based on the estimate of the standard error, unless that is zero where it returns 1. nclass.FD uses the Freedman-Diaconis choice based on the inter-quartile range (IQR) unless that's zero where it reverts to mad(x, constant = 2) and when that is

0

as well, returns 1.

References

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S-PLUS. Springer, page 112. Freedman, D. and Diaconis, P. (1981) On the histogram as a density estimator:

L_{2}

theory. Zeitschrift f<U+00FC>r Wahrscheinlichkeitstheorie und verwandte Gebiete 57, 453--476. Scott, D. W. (1979) On optimal and data-based histograms. Biometrika 66, 605--610. Scott, D. W. (1992) Multivariate Density Estimation. Theory, Practice, and Visualization. Wiley. Sturges, H. A. (1926) The choice of a class interval. Journal of the American Statistical Association 21, 65--66.

Examples

Run this code

set.seed(1)
x <- stats::rnorm(1111)
nclass.Sturges(x)

## Compare them:
NC <- function(x) c(Sturges = nclass.Sturges(x),
      Scott = nclass.scott(x), FD = nclass.FD(x))
NC(x)
onePt <- rep(1, 11)
NC(onePt) # no longer gives NaN

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