[R] R maps Help

[Frank Rodgers]

I am fairly new to R and am plotting flight data on a map. Everything is
working well except the size of the map is really too small to show the data
effectively and I can't seem to figure out how to make the output map
larger. Do I need to change the device characteristics or is it a map.???
call.  Here is the code:

library(maps)
library(geosphere)

airports <- read.csv("airports.csv", header=TRUE)
flights <- read.csv("FSRflights.csv", header=TRUE, as.is=TRUE)

checkDateLine <- function(l){
  n<-0
  k<-length(l)
  k<-k-1
  for (j in 1:k){
    n[j] <- l[j+1] - l[j]
  }
  n <- abs(n)
  m<-max(n, rm.na=TRUE)
  ifelse(m > 30, TRUE, FALSE)
}

clean.Inter <- function(p1, p2, n, addStartEnd){
  inter <- gcIntermediate(p1, p2, n=n, addStartEnd=addStartEnd)
  if (checkDateLine(inter[,1])){
    m1 <- midPoint(p1, p2)
    m1[,1] <- (m1[,1]+180)%%360 - 180
    a1 <- antipode(m1)
    l1 <- gcIntermediate(p1, a1, n=n, addStartEnd=addStartEnd)
    l2 <- gcIntermediate(a1, p2, n=n, addStartEnd=addStartEnd)
    l3 <- rbind(l1, l2)
    l3
  }
  else{
    inter
  }
}

add_lines <- function(){
  pal <- colorRampPalette(c("#00FF00", "#FF0000"))
  colors <- pal(100)

  fsub <- flights[flights$airline == "FSR",]
  fsub <- flights[order(flights$cnt),]
  maxcnt <- max(fsub$cnt)
  
  for (j in 1:length(fsub$airline)) {
    air1 <- airports[airports$iata == fsub[j,]$airport1,]
    air2 <- airports[airports$iata == fsub[j,]$airport2,]
    p1 <- c(air1[1,]$long, air1[1,]$lat)
    p2 <- c(air2[1,]$long, air2[1,]$lat)

    inter <- clean.Inter(p1,p2,n=100, addStartEnd=TRUE)
    colindex <- round( (fsub[j,]$cnt / maxcnt) * length(colors))

    lines(inter, col=colors[colindex], lwd=0.1)
  }  
}


map_usa <- function(){
  xlim <- c(-171.738281, -56.601563)
  ylim <- c(12.039321, 71.856229)
  map("world", col="#191919", fill=TRUE, bg="#736F6E", lwd=0.05, xlim=xlim,
ylim=ylim)
  add_lines()
}

map_world <- function(){
  map("world", col="#191919", fill=TRUE, bg="#736F6E", lwd=.1)
  add_lines()
}

map_world()






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