R - Density
About
The density function
This function computes kernel density estimates.
The algorithm used in density.default disperses the mass of the empirical distribution function over a regular grid of at least 512 points and then uses the fast Fourier transform to convolve this approximation with a discretized version of the kernel and then uses linear approximation to evaluate the density at the specified points.
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Syntax
This function belongs to the stats package
density(x, ...)
## Default S3 method:
density(
x,
bw = "nrd0",
adjust = 1,
kernel = c("gaussian", "epanechnikov", "rectangular", "triangular", "biweight", "cosine", "optcosine"),
weights = NULL,
window = kernel,
width,
give.Rkern = FALSE,
n = 512,
from,
to,
cut = 3,
na.rm = FALSE,
...)
where:
- kernel is the smoothing kernel to be used (default “gaussian”)
Example
Code
data = c(78 ,79 ,84 ,85 ,85 ,86 ,87 ,89 ,89 ,90 ,90 ,92 ,92 ,93 ,95 ,95 ,96 ,97 ,97 ,98)
density(data)
Call:
density.default(x = data)
Data: data (20 obs.); Bandwidth 'bw' = 2.875
x y
Min. : 69.38 Min. :0.000104
1st Qu.: 78.69 1st Qu.:0.005420
Median : 88.00 Median :0.021823
Mean : 88.00 Mean :0.026815
3rd Qu.: 97.31 3rd Qu.:0.050371
Max. :106.62 Max. :0.057345
Plot
Default
hist(data, freq=FALSE, main="Histogram with Density", xlab="")
lines(density(data))
where in the hist function:
- freq= FALSE (or prob=TRUE) means that the histogram graphic is a representation of probability densities (not frequencies) ie the histogram has a total area of one
Ggplot
ggplot(data=dataFrame, aes(dataFrame$Col1)) +
geom_histogram(aes(y =..density..)) +
geom_density(col=2) +
labs(title="Title") +
labs(x="X", y="Frequency Count")
Comparison
sm.density.compare(.., .., xlab = "X Axis Label")