deg2rect: Given position return rectangle code.

In geo: Draw and Annotate Maps, Especially Charts of the North Atlantic

Description

Functions that convert positions in decimal degrees latitude and longitude to rectangle codes for statistical rectangles, their subrectangles or rectangle codes in systems of various resolutions as described below and relating to (see rect2deg).

Usage

d2r(lat, lon = NULL)

d2sr(lat, lon = NULL)

d2mr(lat, lon = NULL, dlat = 5, dlon = 10)

d2dr(lat, lon = NULL, dlat = 1, dlon = 2, startLat = 50)

Arguments

lat,lon	Position(s) as decimal degrees latitude and longitude. If lat is list its components lat$lat and lat$lon are used for lat and lon.
dlat,dlon	Rectangle height and width in degrees and minutes latitude and longitude for d2dr and d2mr respectively.
startLat	Starting latitude used in coding the rectangles.

Details

• r2d with a resolution of 30 min latitue and 1 deg longitude (the Icelandic numbering system, 'tilkynningaskyldureitir').

• sr2d with a resolution of 15 min latitude by 30 min longitude in the Icelandic numbering system for statistical rectangles which starts counting at 60 deg N latitude, with sub-rectangles of 30 min lat by 1 deg lon coded 1, 2, 3 and 4 for the NW, NA, SW and SA quadrants respectively

A small number (1e-06) is added to latitude and subtracted from longitude to ensure rectangle membership of positions on border are “logical” on the nw-hempisphere.

Value

Vector of rectangle codes in the chosen coding system.

Note

These functions could be made hemisphere-aware, and no attention has been given to making the functions work in the southern hemisphere, possibly with the option of specifying starting latitudes.

Author(s)

HB (d2r, d2sr, STJ (d2mr, d2dr).

See Also

rect2deg

Examples

## tally positions in rectangles in object \code{\link{island}} giving
## Iceland's coastline

data(island)
rects <- d2r(island)
table(rects)

geo documentation built on May 29, 2017, 5:36 p.m.