tests/findPeaksAndValleys.R

In aroma.light: Light-Weight Methods for Normalization and Visualization of Microarray Data using Only Basic R Data Types

library("aroma.light")

layout(matrix(1:3, ncol=1))
par(mar=c(2,4,4,1)+0.1)

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# A unimodal distribution
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x1 <- rnorm(n=10000, mean=0, sd=1)
x <- x1
fit <- findPeaksAndValleys(x)
print(fit)
plot(density(x), lwd=2, main="x1")
abline(v=fit$x)

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# A trimodal distribution
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x2 <- rnorm(n=10000, mean=4, sd=1)
x3 <- rnorm(n=10000, mean=8, sd=1)
x <- c(x1,x2,x3)
fit <- findPeaksAndValleys(x)
print(fit)
plot(density(x), lwd=2, main="c(x1,x2,x3)")
abline(v=fit$x)


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# A trimodal distribution with clear separation
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x1b <- rnorm(n=10000, mean=0, sd=0.1)
x2b <- rnorm(n=10000, mean=4, sd=0.1)
x3b <- rnorm(n=10000, mean=8, sd=0.1)
x <- c(x1b,x2b,x3b)

# Illustrating explicit usage of density()
d <- density(x)
fit <- findPeaksAndValleys(d, tol=0)
print(fit)
plot(d, lwd=2, main="c(x1b,x2b,x3b)")
abline(v=fit$x)