Calculate a frequency distribution for two continuous variables.
1 2 3 4 5 6 7 
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. 
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
.
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.
Arni Magnusson.
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.
r2d2package
gives an overview of the package.
1 2 3 4 5 6 7 8 9 10 11 12 13  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))

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