如何使用ggplot2绘制像素网格？

Question

myPalette <- colorRampPalette(rev(brewer.pal(10, "Spectral")))
usamap <- map_data("state")    
ggplot(data=all_data,aes(x=col,y=row,color=m)) + 
      geom_point()+
      scale_colour_gradientn(name = "Flashiness",colours = myPalette(10), limits=c(0,1))+
      geom_polygon( data=usamap, aes(x=long, y=lat,group=group),size=0.3, colour="black",fill=NA)+
      theme_bw()+
      theme(line = element_blank())+
      theme(legend.position = c(.93,.20),panel.grid.major = element_line(colour = "#854440"))+
      ggsave("test.png",width=10, height=8,dpi=300)

给我这个情节

然而，我想要像素/瓷砖，而不是瓷砖/像素相互接触的点。这种性质的东西。

我该怎么做？我尝试使用geom_raster，但我无法使其工作。这是新代码：

ggplot(all_data) +
  geom_raster(aes(x=col, y=row))+
  scale_colour_gradientn(name = "Flashiness",colours = myPalette(100), limits=c(0,1))+
  ggsave("test_pixel.png",width=10, height=8,dpi=300)

新的数字没有颜色，盒子之间也有间隙。

完整数据集：https://www.dropbox.com/s/hrpgk3uqx945hgf/temp.csv?dl=0

数据预览：

dput(head(all_data,10))

structure(list(row = c(48.16, 48.33, 48.15, 48.1, 48.18, 48.14, 
48.23, 48.22, 48.18, 48.14), col = c(-124.7, -124.69, -124.69, 
-124.69, -124.68, -124.68, -124.67, -124.67, -124.67, -124.67
), m = c(0.4713, 0.8998, 0.4891, 0.8418, 0.7998, 0.5292, 0.8115, 
0.8826, 1, 0.5716), flagar = c(0L, 1L, 0L, 1L, 1L, 0L, 1L, 1L, 
1L, 0L), flagk = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), flagsi = c(0L, 
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), flags2o = c(0L, 0L, 0L, 
0L, 0L, 0L, 0L, 0L, 2L, 0L), flagap = c(0L, 0L, 0L, 0L, 0L, 0L, 
0L, 0L, 0L, 0L), flagmt = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 
0L), flagcn = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), flagkf = c(1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), flagrd = c(1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L), flagrv = c(2L, 2L, 2L, 2L, 2L, 2L, 2L, 
2L, 0L, 2L), flagpt = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L
)), .Names = c("row", "col", "m", "flagar", "flagk", "flagsi", 
"flags2o", "flagap", "flagmt", "flagcn", "flagkf", "flagrd", 
"flagrv", "flagpt"), row.names = c(NA, 10L), class = "data.frame")

Answer 1

我认为您需要从点到栅格网格进行空间插值。使用发布的数据

    library(gstat)
    library(sp)
    library(maptools)
    library(viridis)

    # Create a spatial object
    coordinates(dat) = ~x + y

    # Define the extent for spatial interpolation
    x.range <- c(min(dat$x)-0.0125, max(dat$x)+0.0125)
    y.range <- c(min(dat$y)-0.0125, max(dat$y)+0.0125)

    # Create desired grid
    grd <- expand.grid(x = seq(from = x.range[1], to = x.range[2], by = 0.0125), 
                       y = seq(from = y.range[1], to = y.range[2], by = 0.0125))   
    coordinates(grd) <- ~x + y
    gridded(grd) <- TRUE

    # Interpolate using Inverse Distance Weighted 
    idw <- idw(formula = m ~ 1, locations = dat, newdata = grd)  
    # Output clean up
    idw.output = as.data.frame(idw)
    names(idw.output)[1:3] <- c("Longitude", "Latitude", "Flashiness")

    # Plot
    p1 <- ggplot() + geom_tile(data = idw.output, aes(x = Longitude, y = Latitude, fill = Flashiness)) +
      scale_fill_viridis() + geom_point(data = all_data, aes(x = col, y = row, size = m), shape = 21, colour = "red") +
      scale_size_continuous(name = "") +
      theme_bw()
    p1 

结果：

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