alternatives: Determine where an incorrect point record should be placed by showing alternative positions for that point based on common errors in datasets.

Description

This is an interactive plot. The alternative positions are determined by: transposing the x- and y-coordinates, changing the sign on x-coordinate, changing the sign on y-coordinate,changing signs on both coordinates, transposing degrees and minutes, transposing the coordinates but not their signs.

Usage

alternatives(dat, group1 = "Species", group2 = "", 
world, rst, locality = "", pos = "bottomleft", 
ext = c(-180, 180, -60, 90))

Arguments

dat

a dataframe containing fields with the following names: ID, x, y, Species, x_original, y_original, Correction, Modified, Exclude

group1

this is usually the column of species names (default = Species)

group2

this is a second grouping variable

world

a shapefile of the world, where the column containing the country names must be "NAMES"; see data(wrld_simpl)

rst

a raster (see raster package)

locality

a column in the dataframe containing the locality description for the point

pos

position of the legend when group2 is used (e.g. bottomleft)

ext

The extent, which can be specified as c(xmin, xmax, ymin, ymax) default extent c(-180, 180, -90, 90). Alternatively if ext="p" then the extent will be calculated from the coordinates of the points in the dataset.

Value

Details

The user starts by clicking on a record of interest. Then alternative positions for that record are displayed using purple point symbols. All other records for that particular species are indicated in black. The user then clicks on the position of the correct record, or back on the originally selected record to exclude it. If none of the alternative points are correct then the stop button should be selected (top left of plot screen). The identifier (ID) of the record is displayed next to the point and its coordinates and species name are displayed at the top of the map. Once a new position for the point is selected then the new coordinates for that point are displayed at the bottom of the map. When a record is changed then all records with identical x- and y-coordinates will also be changed in the same way. This is because several different species may have been collected at the same locality.

Examples

Run this code

## Not run: 
# dem<-raster(dem,xmn=-180, xmx=180, ymn=-60, ymx=90)
# dat<-alternatives(dat,group1="Species",group2="",world,dem,locality="",pos="bottomleft",ext="p")## End(Not run)