freq2d {r2d2} | R Documentation |
Bivariate (Two-Dimensional) Frequency Distribution
Description
Calculate a frequency distribution for two continuous variables.
Usage
freq2d(x, ...)
## S3 method for class 'formula'
freq2d(formula, data, subset, ...)
## Default S3 method:
freq2d(x, y, n=20, pad=0, layout=1, print=TRUE, dnn=NULL, ...)
Arguments
x |
a vector of x values, or a data frame whose first two columns contain the x and y values. |
y |
a vector of y values. |
formula |
a |
data |
a |
subset |
an optional vector specifying a subset of observations to be used. |
n |
the desired number of bins for the output, a scalar or a vector of length 2. |
pad |
number of rows and columns to add to each margin, containing only zeros. |
layout |
one of three layouts for the output: |
print |
whether to display the resulting matrix on the screen using dots for zeros. |
dnn |
the names to be given to the dimensions in the result. |
... |
named arguments to be passed to the default method. |
Details
The exact number of bins is determined by the
pretty
function, based on the value of n
.
Padding the margins with zeros can be helpful for subsequent analysis, such as smoothing.
The print
logical flag only has an effect when layout=1
.
Value
The layout
argument specifies one of the following formats for
the binned frequency output:
matrix
that is easy to read, aligned like a scatterplot.list
with three elements (x, y, matrix) that can be passed to various plotting functions.data.frame
with three columns (x, y, frequency) that can be analyzed further.
Author(s)
Arni Magnusson.
See Also
cut
, table
, and print.table
are the basic underlying functions.
hist2d
in the gplots package is a related
function with graphical capabilities.
conf2d
calculates a bivariate empirical confidence
region, a smooth polygon.
r2d2-package
gives an overview of the package.
Examples
freq2d(Ushape)
freq2d(quakes$long, quakes$lat, dnn="")
freq2d(lat~long, quakes, n=c(10,20), pad=1)
# Supress display
freq2d(saithe)
range(freq2d(saithe, print=FALSE))
# Layout, plot
freq2d(saithe, layout=2)
freq2d(saithe, layout=3)
contour(freq2d(saithe, layout=2))
lattice::contourplot(Freq~Bio+HR, freq2d(saithe,layout=3))