non_package_files/new_ideas/compress_plots.R

In tdanker/ephys2: Read, analyze and plot HEKA Patchmaster files

device_xbreaks<-function(){
  usr_x_range<-par("usr")[1:2] #x
  usr_x_pixel_range<-floor(grconvertX(usr_x_range, from="user", to="device"))
  usr_x_pixels <- usr_x_pixel_range[1] : usr_x_pixel_range[2]
  return( grconvertX(usr_x_pixels + .0, from="device", to="user") )
}


compress<-function(xy){
  breaks<-device_xbreaks()
  cuts = findInterval(xy$x,breaks);
  suppressMessages(library(data.table))
  
  dt = data.table(x=xy$x,y=xy$y,cuts=cuts)
  
  dmax = dt[,list(x=max(x),y=max(y)),keyby="cuts"]
  dmax$cuts=NULL;
  
  dmin = dt[,list(x=min(x),y=min(y)),keyby="cuts"]
  dmin$cuts=NULL;
  n=nrow(dmin)
  s <- rep(1:n, each = 2) + (0:1) * n
  return( rbind(dmin,dmax)[s,] )
}

# test data
xy=NULL
xy$x=1:100000/10000
xy$y=rnorm(length(xy$x))

# first, initialize plot area so that compress can work on its coordinates
plot(NULL, xlim=range(xy$x), ylim=range(xy$y))
points(compress(xy), ty="l", col="black")  # fast
points(xy, ty="l", col="red")              # slow, ~100% overlap
points(compress(xy), ty="l", col="blue")   # fast, ~100% overlap