contourLines {grDevices} | R Documentation |

## Calculate Contour Lines

### Description

Calculate contour lines for a given set of data.

### Usage

contourLines(x = seq(0, 1, len = nrow(z)),
y = seq(0, 1, len = ncol(z)),
z, nlevels = 10,
levels = pretty(range(z, na.rm=TRUE), nlevels))

### Arguments

`x,y` |
locations of grid lines at which the values in `z` are
measured. These must be in ascending order. By default, equally
spaced values from 0 to 1 are used. If `x` is a `list` ,
its components `x$x` and `x$y` are used for `x`
and `y` , respectively. If the list has component `z` this
is used for `z` . |

`z` |
a matrix containing the values to be plotted (`NA` s are
allowed). Note that `x` can be used instead of `z` for
convenience. |

`nlevels` |
number of contour levels desired **iff**
`levels` is not supplied. |

`levels` |
numeric vector of levels at which to draw contour
lines. |

### Details

`contourLines`

draws nothing, but returns a set of contour lines.

There is currently no documentation about the algorithm.
The source code is in ‘`$R_HOME/src/main/plot3d.c`’.

### Value

A list of contours.
Each contour is a list with elements:

`level ` |
The contour level. |

`x ` |
The x-coordinates of the contour. |

`y ` |
The y-coordinates of the contour. |

### See Also

`contour`

.

### Examples

x <- 10*1:nrow(volcano)
y <- 10*1:ncol(volcano)
contourLines(x, y, volcano)

[Package

*grDevices* version 2.2.1

Index]