Bivariate (Two-Dimensional) Frequency Distribution
Calculate a frequency distribution for two continuous variables.
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, ...)
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.
r2d2-package gives an overview of the package.
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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