marmap (version 1.0.10)

get.depth: Get depth data by clicking on a map

Description

Outputs depth information based on points selected by clicking on a map

Usage

get.depth(mat, x, y=NULL, locator=TRUE, distance=FALSE, ...)

Value

A data.frame with at least, longitude, latitude and depth with one line for each point of interest. If distance=TRUE, a fourth column containing the kilometric distance from the first point is added.

Arguments

mat

Bathymetric data matrix of class bathy, as imported with read.bathy.

x

Either a list of two elements (numeric vectors of longitude and latitude), a 2-column matrix or data.frame of longitudes and latitudes, or a numeric vector of longitudes.

y

Either NULL (default) or a numerical vector of latitudes. Ignored if x is not a numeric vector.

locator

Logical. Whether to choose data points interactively with a map or not. If TRUE (default), a bathymetric map must have been plotted and both x and y are both ignored.

distance

whether to compute the haversine distance (in km) from the first data point on (default is FALSE). Only available when at least two points are provided.

...

Further arguments to be passed to locator when the interactive mode is used (locator=TRUE).

Author

Benoit Simon-Bouhet and Eric Pante

Details

get.depth allows the user to get depth data by clicking on a map created with plot.bathy or by providing coordinates of points of interest. This function uses the locator function (graphics package); after creating a map with plot.bathy, the user can click on the map once or several times (if locator=TRUE), press the Escape button, and get the depth of those locations in a three-coumn data.frame (longitude, latitude and depth). Alternatively, when locator=FALSE, the user can submit a list of longitudes and latitudes, a two-column matrix or data.frame of longitudes and latitudes (as input for x), or one vector of longitudes (x) and one vector of latitudes (y). The non-interactive mode is well suited to get depth information for each point provided by GPS tracking devices. While get.transect gets every single depth value available in the bathymetric matrix between two points along a user-defined transect, get.depth only provides depth data for the specific points provided as input by the user.

See Also

path.profile, get.transect, read.bathy, summary.bathy, subsetBathy, nw.atlantic

Examples

# load NW Atlantic data and convert to class bathy
data(nw.atlantic)
atl <- as.bathy(nw.atlantic)

# create vectors of latitude and longitude
lon <- c(-70, -65, -63, -55)
lat <- c(33, 35, 40, 37)

# a simple example
plot(atl, lwd=.5)
points(lon,lat,pch=19,col=2)

# Use get.depth to get the depth for each point
get.depth(atl, x=lon, y=lat, locator=FALSE)

# alternativeley once the map is plotted, use the iteractive mode:
if (FALSE) {
get.depth(atl, locator=TRUE, pch=19, col=3)
}
# click several times and press Escape