trapezoid.R
In trapezoid: The Trapezoidal Distribution

### R code from vignette source 'trapezoid.Rnw'

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### code chunk number 1: trapezoid.Rnw:53-55
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options(width = 70)
options(continue=" ")


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### code chunk number 2: trapezoid
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# plyr and ggplot2 are required for these examples
require(trapezoid)
require(plyr)
require(ggplot2)

# Trapezoid
x <- seq(from = 0, to = 1, by = 0.01)	
density <- dtrapezoid(x, min = 0, mode1 = 1/3, mode2 = 2/3, max = 1,
	n1 = 2, n3 = 2, alpha = 1)
trapezoid <- ggplot(data = data.frame(x, density), 
		aes(x = x, y = density)) + geom_line() + theme_bw()
print(trapezoid)


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### code chunk number 3: triangle
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# Triangle
x <- seq(from = 0, to = 1, by = 0.01)	
density <- dtrapezoid(x, min = 0, mode1 = 1/2, mode2 = 1/2, max = 1,
	n1 = 2, n3 = 2, alpha = 1)
triangle <- ggplot(data = data.frame(x, density), 
				aes(x = x, y = density)) + geom_line() + theme_bw()
print(triangle)


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### code chunk number 4: generalizedTrapezoids
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# Generalized trapezoidal distributions
x <- seq(from = 0, to = 1, by = 0.01)	

# Create a lists of arguments, varying n1, n3, and alpha
arguments <- list()
arguments[['A']] <- list(x = x, n1 = 2, n3 = 2, alpha = 0.8)
arguments[['B']] <- list(x = x, n1 = 1.5, n3 = 1.5, alpha = 1)
arguments[['C']] <- list(x = x, n1 = 2.5, n3 = 2.5, alpha = 1.5)
arguments[['D']] <- list(x = x, n1 = 1.5, n3 = 2.5, alpha = 0.5)
arguments[['E']] <- list(x = x, n1 = 2.5, n3 = 1.5, alpha = 1)
arguments[['F']] <- list(x = x, n1 = 0.5, n3 = 0.5, alpha = 1.5)
arguments[['G']] <- list(x = x, n1 = 1.5, n3 = 0.5, alpha = 0.5)
arguments[['H']] <- list(x = x, n1 = 2.5, n3 = 0.5, alpha = 1)
arguments[['I']] <- list(x = x, n1 = 0.5, n3 = 1.5, alpha = 1.5)
arguments[['J']] <- list(x = x, n1 = 0.5, n3 = 2.5, alpha = 0.5)

# Calculate the distributions
plot.data <- ldply(arguments, function(z)
{
  x <- z$x
  density <- dtrapezoid(x = z$x, min = 0, mode1 = 0.2, mode2 = 0.8,
    max = 1, n1 = z$n1, n3 = z$n3, alpha = z$alpha)
  args <- paste("n1 = ", z$n1, ", n3 = ", z$n3, ", alpha = ", z$alpha, 
    sep="", collapse="")
  out <- data.frame(x, density, args)
})

# Create labels for later use in displaying the arguments on the plots 
plot.data$label <- paste(plot.data$.id, ": ", plot.data$args, sep="")

# Create plots
generalizedTrapezoids <- ggplot(data = plot.data, aes(x = x, y = density)) + 
  geom_line() + theme_bw() + 
  facet_wrap(~label, ncol = 2, scales = "free_y")
print(generalizedTrapezoids)