Plotting Ship Paths

rm(list=ls())
source("SQLFunctions.R")

plotSet = function(filename,dck=701,alpha=.01,lwd=8) {
  library(grid)
  paths = tbl(tblsrc,"paths") %.% 
    filter(DCK==dck) %.% 
    arrange(voyagenum,yearday) %.% 
    select(LON,LAT,voyagenum) %.% 
    collect()
    
  paths = paths %.% mutate(LON=LON+180)
  paths$LON[paths$LON<0] = paths$LON[paths$LON<0] + 360
  paths$LON[paths$LON>360] = paths$LON[paths$LON>360] - 360
  
  #break groups that cross from 0 to 360 or vice versa, which otherwise leave streaks
  paths$split = c(0,abs(paths$LON[-1]-paths$LON[1:(nrow(paths)-1)])>20)
  paths$segment = 100*paths$voyagenum + cumsum(paths$split)
  
  
  #desperately try to remove all elements: code stole from stack overflow, somewhere.
  new_theme_empty <- theme_bw()
  new_theme_empty$line <- element_blank()
  new_theme_empty$rect <- element_blank()
  new_theme_empty$strip.text <- element_blank()
  new_theme_empty$axis.text <- element_blank()
  new_theme_empty$plot.title <- element_blank()
  new_theme_empty$axis.title <- element_blank()
  new_theme_empty$plot.margin <- structure(c(0, 0, -1, -1), unit = "lines", valid.unit = 3L, class = "unit")
  
  plotting = paths
  
  #Actually make the plot:
  plot = ggplot(plotting,
                aes(x=LON,y=LAT,group=segment)) + 
    geom_path(alpha=alpha,lwd=lwd) +
    labs(x="",y="",title="") + 
    theme(line=element_blank(),
          rect=element_blank(),
          axis.text=element_blank()
    )+ coord_equal() + scale_x_continuous(expand=c(0,0),limits=c(0,360)) + 
    scale_y_continuous(expand=c(0,0),limits=c(-90,90))
  
  png(filename=filename,width=4096*2,height=2048*2)
  
  #plotting code from: [whoops forgot to paste it in, but SO somewhere again]
  #plots just the central panel, which makes it compatible with the format Science on a Sphere wants.
  gt <- ggplot_gtable(ggplot_build(plot))
  ge = subset(gt$layout,name=="panel")
  grid.draw(gt[ge$t:ge$b, ge$l:ge$r])
  graphics.off()
}



dcks = tbl(tblsrc,"voyages") %.% 
  group_by(DCK) %.% summarize(count=n(),points=sum(points)) %.% 
  arrange(-count) %.% collect()
dcks %.% filter(points<3000000,points>10000) %.%
  group_by(DCK) %.% 
  do(function(row) {
    dck = row$DCK[1]
    filename = paste0("~/Dropbox/",dck,"-2.png")
    if (!file.exists(filename))  {
    plotSet(filename=filename,dck=dck,alpha=.04,lwd=3)  
    }
})