rworldmap: addMapLegendBoxes – R documentation

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addMapLegendBoxes

Add a legend of coloured boxes to a map

Description

Creates a colour box legend, showing the range of colours and the values the colours correspond to. This works well for categorical data with relatively few categories.

Usage

addMapLegendBoxes(cutVector = "", colourVector = "", x = "bottomleft",
  horiz = FALSE, title = "category", cex = 1, pt.cex = 2,
  col = "gray", bg = "white", legendText = "",
  catMethod = "categorical", plottedData = "", colourPalette = "heat",
  sigFigs = 2, missingCountryCol = "white", ...)

Arguments

`cutVector`	the categories or breaks used in the map
`colourVector`	colours used in the map
`x`	positioning of legend e.g. 'bottomleft', 'topright'
`horiz`	if TRUE horizontal legend
`title`	title for Legend
`cex`	controls the font size, default is 1
`pt.cex`	controls size of colour boxes relative to cex, default is 2
`col`	colour for boundary of colour boxes, default is "gray"
`bg`	colour for legend background, default is "white", NA makes the legend background transparent
`legendText`	the text to put against each legend box, if left blank cutVector is used, needs to be a vector the same length as length cutVector
`catMethod`	the categorisation method used influences what text added to legend elements, for 'categorical' just the category names are used for other options limits are used
`plottedData`	not used yet but maybe in future
`colourPalette`	not used yet but maybe in future
`sigFigs`	not used yet but maybe in future
`missingCountryCol`	not used yet but maybe in future
`...`	to allow other params to be set in legend

Details

This creates a legend with separate boxes of colour rather than addMapLegend() which creates a colour bar. This method is used as the default for categorical data.

See the examples for how to use a parameter list returned from mapping functions.

Value

Adds a legend to a plot.

Author(s)

Andy South

Examples

#Set up the plot so the world map uses the full width.
mapDevice() 
#map example categorical data with no legend              
mapParams <- mapCountryData(nameColumnToPlot='GEO3major'
              , catMethod='categorical'
              , addLegend='FALSE' 
              )
              
#add default legend using the same parameters as mapCountryData               
do.call( addMapLegendBoxes, c( mapParams))

#adding a modified legend by specifying extra parameters               
do.call( addMapLegendBoxes, c(mapParams,x='bottom',horiz=TRUE,title="Region"))

#user defined map colour sceme              
mapParams <- mapCountryData(nameColumnToPlot='GEO3major'
              , catMethod='categorical'
              , addLegend='FALSE'
              , colourPalette=c('white','green','red','yellow','blue','black') 
              )
#changing legendText
mapParams$legendText <- c('antarctic','africa','oceania'
                         ,'americas','s.asia','eurasia')              
do.call( addMapLegendBoxes, c(mapParams,x='bottom',title="Region",horiz=TRUE))

#or this way
#do.call( addMapLegendBoxes
#        , c(mapParams
#           ,list(legendText=c('antarctic','africa','oceania'
#                              ,'americas','s.asia','eurasia')
#                ,x='bottom',title="Region",horiz=TRUE)))

rworldmap

Mapping Global Data

v1.3-6

GPL (>= 2)

Authors