biv.test {adehabitat} | R Documentation

## Bivariate Test

### Description

`biv.plot` displays a bivariate plot. `biv.test` displays the results of a bivariate randomisation test.

### Usage

    biv.plot(dfxy, br = 10, points = TRUE, density = TRUE,
             kernel = TRUE, o.include = FALSE, pch, cex, col, h, sub,
             side = c("top", "bottom", "none"), ...)
    biv.test(dfxy, point, br = 10, points = TRUE, density = TRUE,
             kernel = TRUE, o.include = FALSE, pch, cex, col, Pcol, h, sub,
             side = c("top", "bottom", "none"), ...)

### Arguments

`dfxy` | a data frame with N lines (couples of values) and two columns
`br` | a parameter used to define the numbers of breaks of the histograms. A larger value leads to a larger number of breaks
`points` | logical. Whether the points should be displayed
`density` | logical. Whether the kernel density estimation should be displayed for the marginal histograms
`kernel` | logical. Whether the kernel density estimation should be displayed for the bivariate plot
`o.include` | logical. If `TRUE`, the origin is included in the plot
`pch` | plotting "character", i.e., symbol to use for the points. (see `?points`)
`cex` | character expansion for the points
`col` | color code or name for the points, see `?par`
`h` | vector of bandwidths for x and y directions, used in the function `kde2d` of the package `MASS`. Defaults to normal reference bandwidth (see `?kde2d`)
`sub` | a character string to be inserted in the plot as a title
`side` | if `"top"`, the x and y scales of the grid are upside, if `"bottom"` they are downside, if `"none"` no legend
`point` | a vector of length 2, representing the observation to be compared with the simulated values of the randomisation test
`Pcol` | color code or name for the observed point
`...` | further arguments passed to or from other methods

### Details

`biv.test` is used to display the results of a bivariate randomisation test. An example of use of the function is provided in the function `niche.test`.

The x-axis of the main window corresponds to the first column of `dfxy`; the y-axis corresponds to the second column. Kernel density is estimated to indicate the contours of the distribution of randomised values. The two marginal histograms correspond to the univariate tests on each axis, for which the p-values are computed with `as.randtest` (one-sided tests).

### Warning

`biv.plot` and `biv.test` uses the function `kde2d` of the package `MASS`.

### Author(s)

Mathieu Basille basille@biomserv.univ-lyon1.fr

### See Also

`as.randtest`, `niche.test`

### Examples

    ## Not run:
    x = rnorm(1000,2)
    y = 2*x+rnorm(1000,2)
    dfxy = data.frame(x, y)

    biv.plot(dfxy)
    biv.plot(dfxy, points=F, col="lightblue", br=20)

    p = c(3, 4)
    biv.test(dfxy, p)
    biv.test(dfxy, p, points=F, Pcol="darkred", col="lightblue", br=20)
    ## End(Not run)

[Package adehabitat version 1.4 Index]