plotpdf | R Documentation |
Plot a probability denstity function with x-axis limits determined by quantiles of the distribution. Quantiles are computed using a quantile function or cumulative distribution function, whichever is supplied.
plotpdf(pdf, qdf, cdf, lq = 0.01, uq = 0.99, ...)
pdf |
probability density to be plotted, a function. |
qdf |
quantile function to be used for computation of quantiles, a function. |
cdf |
cumulative distribution function to be used for computation of quantiles,
a function. This argument is used if |
lq |
lower quantile, used in the computation of the left limit. |
uq |
upper quantile, used in the computation of the right limit. |
... |
additional arguments to be passed on to the |
The function plots pdf(x)
over the interval (xmin,xmax) where
xmin and xmax are the lq
th and uq
th quantiles,
respectively, of the distribution. The quantile function,
qdf
, is used, if supplied. Otherwise the quantiles are computed
numerically from the cdf.
Argument pdf
is not required to be a pdf, it may be any
function. For example, the same way of choosing the limits may be
appropriate for a plot of the cdf, see the examples.
Similarly, qdf
and cdf
need not be related to pdf
.
Georgi N. Boshnakov
cdf2quantile
pdf1 <- function(x) dnorm(x, mean = 100, sd = 5) qdf1 <- function(x) qnorm(x, mean = 100, sd = 5) cdf1 <- function(x) pnorm(x, mean = 100, sd = 5) plot(pdf1) # needs to specify 'from' and 'to' args for meaningful plot plotpdf(pdf1, qdf1) # using quantile function plotpdf(pdf1, cdf = cdf1) # using cdf plotpdf(pdf1, cdf = cdf1, lq = 0.001, uq = 0.999) # ... and non-default quantiles plotpdf(cdf1, cdf = cdf1, lq = 0.001, uq = 0.999) # plot a cdf ## a mixture distribution: pf1 <- function(x){ 0.25 * pnorm(x, mean = 3, sd = 0.2) + 0.75 * pnorm(x, mean = -1, sd = 0.5) } df1 <- function(x){ 0.25 * dnorm(x, mean = 3, sd = 0.2) + 0.75 * dnorm(x, mean = -1, sd = 0.5) } plotpdf(df1, cdf = pf1) # plot the pdf plotpdf(pf1, cdf = pf1) # plot the cdf c(cdf2quantile(0.05, pf1), cdf2quantile(0.95, pf1))
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