View difference between Paste ID: vYaSvhqS and BjZpARdm

 ggproj <- function(r, lat, lon, tolerance=0.001, plot.borders=TRUE, border.color='black') {
     #r, lat, lon must be rasterLayers
     #Adapted from
     #http://stackoverflow.com/questions/43612903/how-to-properly-plot-projected-gridded-data-in-ggplot2
     if (!compareRaster(r, lat, lon)) {stop('Inputs should have the same size and projection')}
     require(ggplot2) #needs ggplot >= 2.2.1.9000
     require(sf)
     require(sp)
     crs <- projection(r)
 
     coords = data.frame(lat = values(lat), lon = values(lon))
     spPoints <- SpatialPointsDataFrame(coords,
                                       data = data.frame(data = values(r)),
                                       proj4string = CRS("+init=epsg:4326"))
     orig_grid = spTransform(spPoints, crs)
     polys = as(SpatialPixelsDataFrame(orig_grid, orig_grid@data, tolerance = tolerance),"SpatialPolygonsDataFrame")
     polys_sf = as(polys, "sf")
-    points_sf = as(orig_grid, "sf")
+
     gg <- ggplot(polys_sf) +
         geom_sf(aes(fill = data), color = "transparent") +
         theme_bw() +
         theme(panel.ontop=TRUE, panel.background=element_blank()) +
         scale_x_continuous(expand = c(0, 0)) +
         scale_y_continuous(expand = c(0, 0))
 
     if (plot.borders) {
         require(maps)
         borders <- sf::st_as_sf(map('world', plot = FALSE, fill = TRUE))
         gg <- gg +
                geom_sf(data = borders, fill = "transparent", color = border.color) +
                coord_sf(crs = st_crs(crs),
                         xlim = st_bbox(polys_sf)[c(1,3)],
                         ylim = st_bbox(polys_sf)[c(2,4)]
                 )
     }
     return(gg)
 }