plot.mix: Mix Object Plotting

In mixdist: Finite Mixture Distribution Models

Description

A function for plotting of Mix objects. It is called via the generic function plot.

Usage

## S3 method for class 'mix'
plot(x, mixpar = NULL, dist = "norm", root = FALSE, ytop = NULL, 
     clwd = 1, main, sub, xlab, ylab, bty, BW = FALSE, ...)

Arguments

x	an object of class "mix", usually, the results returned by the model fitting function mix.
mixpar	NULL or a data frame containing the values for parameters of component distributions, which are, in order, the proportions, means, and standard deviations.
dist	the distribution of components, it can be "norm", "lnorm", "gamma", "weibull", "binom", "nbinom" and "pois".
root	if TRUE, a hanging rootogram will be displayed.
ytop	a scalar which determines the top of the y-axis.
clwd	a positive number denoting line width, defaulting to 1.
main	an overall title for the plot.
sub	a subtitle for the plot.
xlab	a title for the x-axis.
ylab	a title for the y-axis.
bty	A character string which determined the type of box which is drawn about plots. If bty is one of "o", "l", "7", "c", "u", or "]" the resulting box resembles the corresponding upper case letter. A value of "n" suppresses the box.
BW	logical; if TRUE the plot will be drawn in black and white.
...	additional arguments to the function plot.default.

Details

If the argument x gives an object of class "mix", the plot will be a histogram for the grouped data which come from the element mixdata of x. Although the leftmost (first) and rightmost (mth) intervals are always open-ended, on the histogram the first interval is shown as being twice the width of the second interval and the mth is shown as being twice the width of the m - 1st interval. When the fitted distribution is one of "lnorm", "gamma" and "weibull", the left boundary of the first interval will be taken zero since negative values and zeroes are not allowed for these distribution. For the distributions "binom", "nbinom" and "pois" negative data are not permitted, so the left boundary of the first interval is taken -0.5. The component distributions weighted by their respect proportions and the mixture distribution are computed by the estimated parameter values from the element parameters of x, and superimposed on the histogram. The distribution of components will be taken the value of the element distribution. If sub, xlab, ylab and bty are not specified, the default values will be used. The positions of the means are indicated with triangles. When the argument root is TRUE, a hanging rootogram will be displayed, that is, if only grouped data are given, this option plots the histogram with the square root of relative frequency on the y-axis. If there is a model as well as data, not only is the y-axis the square root of relative frequency, also the bars of the histogram, instead of rising from 0, are shifted up or down so that the mid-point of the top of the bar is exactly on the curve indicating the mixture distribution and the bottom of the bar may therefore be above or below the x-axis. If the bar goes below the x-axis, the portion below is shown as a blue rectangle. If the bar does not reach the x-axis, the space between the bottom of the bar and the x-axis is shown as a blue rectangle. If the blue rectangles are almost above or below in an area of the x-axis, we may say that the mixture curve around that area is not fitting well.

See Also

mixparam for organizing the parameter values, mix for fitting mixture model, plot.mixdata for plotting Mixdata objects, plot.default for additional arguments.

Examples

data(pike65)
data(pikepar)
fit1 <- mix(pike65, pikepar, "lnorm",
            constr = mixconstr(consigma = "CCV"), emsteps = 3)
plot(fit1)
plot(fit1, root = TRUE)
data(bindat)
data(binpar)
fit2 <- mix(bindat, binpar, "binom",
            constr = mixconstr(consigma = "BINOM", size = c(20, 20, 20, 20)))
plot(fit2)
plot(fit2, root = TRUE)

mixdist documentation built on May 2, 2019, 3:34 p.m.