identifyCountries: a function that will print country name and attribute values when a user clicks on the map

Description

An interactive function that will print on a map the nearest country name to a user mouse click. The user can specify nothing and the function will use a map from the package. Alternatively the user can specifiy a data frame or SpatialPolygonsDataFrame in which case they need to define the column containing the country names (nameCountryColumn) and optionally a 2nd attribute column to print (nameColumnToPlot).

Usage

identifyCountries(dF = ""
                 , nameCountryColumn = "NAME"
                 , nameX = "LON"
                 , nameY = "LAT"
                 , nameColumnToPlot = ""
                 , plotSelected = FALSE
                 , ...)

Arguments

data frame or SpatialPolygonsDataFrame

nameCountryColumn

name of column containing country names to be printed on the map (could also be set to any other attribute the user wants to query)

nameX

name of column containing the X variable (longitude), not needed if dF is a SpatialPolygonsDataFrame

nameY

name of column containing the Y variable (lattitude), not needed if dF is a SpatialPolygonsDataFrame

nameColumnToPlot

name of an attribute column in the data frame the value of which will be appended to the country name when it is printed

plotSelected

if set to TRUE a blue outline will be printed around the countries selected when the selection process is finished

...

other parameters that can be passed to identify()

Value

a vector of the indices of the countries selected

Details

Uses the identify() function, which waits for the user to click on the map, and stops when the user right clicks and selects 'stop'. It uses country centroids, and will give a warning if one is too far away (default value of 0.25 inches).

Examples

Run this code

#mapCountryData()
#identifyCountries()

#identifyCountries(nameColumnToPlot = "POP_EST", plotSelected = TRUE)