绘制大圆路径

Question

我试图绘制一些基于路径/连接的地图，但我无法弄清楚如何。

我看到一个基于点的指标（伦敦的犯罪热点，googleVis，ggmap等等）的很多可能性，但我找不到太多基于两点的指标的例子（城市之间的移民） ，列车路线等。包geosphere有一个示例，但它似乎不适用于R 3.0.2。

理想情况下，我想要这样的D3 example，并且还想要自定义线条和圆圈的厚度，颜色等。

PS：我不认为rCharts可以做到这一点，对吗？

Answer 1

这是我去年开始做的事情，从来没有适当地进行抛光，但希望它应该回答你在地图上用大圆线连接点的问题，可灵活定制线条，圆圈等。

我使用（我的）rworldmap包进行映射，使用WDI进行世界银行数据，使用geosphere进行大圆线。目的是绘制从所有捐助国到所有受援国的援助流量（每个捐助者一个地块）。下面是一个示例图，下面是代码。希望能帮助到你。很高兴有时间再次拿起它！ 安迪

library(rworldmap)
library(WDI) # WORLD BANK INDICATORS

## lines of either type may obscure more than they add
##**choose line option here
addLines <- 'gc' #'none''straight' 'gc'
if ( addLines == 'gc' ) library(geosphere)

# setting background colours
oceanCol = rgb(7,0,30,maxColorValue=255) 
landCol = oceanCol 

#produces a list of indicator IDs and names as a matrix
indicatorList <- WDIsearch('aid flows')

#setting up a world map shaped plot window
#*beware this is windows specific
mapDevice('windows',width=10,height=4.5)


year <- 2000
#for(indNum in 1:2)
for(indNum in 1:nrow(indicatorList))
{
  indID <- indicatorList[indNum][1]
  donorISO3 <- substr(indID,start=8,stop=10)

  dFdonor <- WDI(indicator=indID,start=year,end=year)
  #divide by 10^6 for million dollars
  dFdonor[indID] <- dFdonor[indID] * 1/10^6

  sPDFdonor <- joinCountryData2Map(dFdonor,nameJoinColumn='country',joinCode='NAME')
  #take out Antarctica
  sPDFdonor <- sPDFdonor[-which(row.names(sPDFdonor)=='Antarctica'),]

  legendTitle=paste("aid flow from",donorISO3,year,"(millions US$)") 
  mapBubbles(sPDFdonor, nameZSize=indID, plotZeroVals=FALSE, legendHoriz=TRUE, legendPos="bottom", fill=FALSE, legendTitle=legendTitle, oceanCol=oceanCol, landCol=landCol,borderCol=rgb(50,50,50,maxColorValue=255),lwd=0.5,lwdSymbols=1)
  #removed because not working , main=paste('donor', donorISO3,year)

  #now can I plot lines from the centroid of the donor to the centroids of the recipients
  xDonor <- sPDFdonor$LON[ which(sPDFdonor$ISO3==donorISO3) ]
  yDonor <- sPDFdonor$LAT[ which(sPDFdonor$ISO3==donorISO3) ] 
  xRecips <- sPDFdonor$LON[ which(sPDFdonor[[indID]] > 0) ]
  yRecips <- sPDFdonor$LAT[ which(sPDFdonor[[indID]] > 0) ]
  amountRecips <- sPDFdonor[[indID]][ which(sPDFdonor[[indID]] > 0) ]


  ## straight lines
  if ( addLines == 'straight' )
  {
    for(line in 1:length(xRecips))
    {  
       #col <- 'blue'
       #i could modify the colour of the lines by the size of the donation
       #col=rgb(1,1,1,alpha=amountRecips[line]/max(amountRecips))
       #moving up lower values
       col=rgb(1,1,0,alpha=sqrt(amountRecips[line])/sqrt(max(amountRecips)))
       lines(x=c(xDonor,xRecips[line]),y=c(yDonor,yRecips[line]),col=col, lty="dotted", lwd=0.5)   #lty = "dashed", "dotted", "dotdash", "longdash", lwd some devices support <1
    }
  }

  ## great circle lines
  ## don't work well when donor not centred in the map
  ## also the loop fails at CEC & TOT because not ISO3 codes
  if ( addLines == 'gc' & donorISO3 != "CEC" & donorISO3 != "TOT" )
  {  
    for(line in 1:length(xRecips))
    {
      #gC <- gcIntermediate(c(xDonor,yDonor),c(xRecips[line],yRecips[line]), n=50, breakAtDateLine=TRUE)
      #30/10/13 lines command failed with Error in xy.coords(x, y) : 
      #'x' is a list, but does not have components 'x' and 'y'
      #adding sp=TRUE solved
      gC <- gcIntermediate(c(xDonor,yDonor),c(xRecips[line],yRecips[line]), n=50, breakAtDateLine=TRUE, sp=TRUE)

      #i could modify the colour of the lines by the size of the donation
      #col=rgb(1,1,1,alpha=amountRecips[line]/max(amountRecips))
      #moving up lower values
      col=rgb(1,1,0,alpha=sqrt(amountRecips[line])/sqrt(max(amountRecips)))

      lines(gC,col=col,lwd=0.5)
    }
  }  

  #adding coasts in blue looks nice but may distract
  data(coastsCoarse)
  plot(coastsCoarse,add=TRUE,col='blue')

  #repeating mapBubbles with add=T to go on top of the lines
  mapBubbles(sPDFdonor, nameZSize=indID, plotZeroVals=FALSE, fill=FALSE, addLegend=FALSE, add=TRUE, ,lwd=2)
  #removed because not working : , main=paste('donor', donorISO3,year)

  #looking at adding country labels
  text(xRecips,yRecips,sPDFdonor$NAME[ which(sPDFdonor[[indID]] > 0) ],col=rgb(1,1,1,alpha=0.3),cex=0.6,pos=4) #pos=4 right (1=b,2=l,3=ab)

  #add a title 
  nameDonor <- sPDFdonor$NAME[ which(sPDFdonor$ISO3==donorISO3) ]
  mtext(paste("Aid flow from",nameDonor,year), cex = 1.8, line=-0.8)

  #savePlot(paste("C:\\rProjects\\aidVisCompetition2012\\Rplots\\greatCircles\\wdiAidFlowLinesDonor",donorISO3,year,sep=''),type='png')
  #savePlot(paste("C:\\rProjects\\aidVisCompetition2012\\Rplots\\greatCircles\\wdiAidFlowLinesDonor",donorISO3,year,sep=''),type='pdf')

} #end of indNum loop