具有指定z範圍的R底圖多邊形地圖？

Question

我想生成一組具有一致顏色漸變的地圖，並且有點卡住了。我知道如何做我想要的柵格，但不是矢量數據。

這是我想要的柵格的行爲：

require(raster) 
r1=raster(matrix(sample(1:50,16),4,4)) 
r2=raster(matrix(sample(1:100,16),4,4)) 
plot(r1,col=colorRampPalette(c("red","white","blue"))(10),zlim=c(0,100)) 
plot(r2,col=colorRampPalette(c("red","white","blue"))(10),zlim=c(0,100)) 

我如何與多邊形類似的地圖？

例如：我剛剛想出了

poly1=rasterToPolygons(r1) 
poly2=rasterToPolygons(r2) 

Answer 1

# Your previous code... 
require(raster) 
r1=raster(matrix(sample(1:50,16),4,4)) 
r2=raster(matrix(sample(1:100,16),4,4)) 
poly1=rasterToPolygons(r1) 
poly2=rasterToPolygons(r2) 
################################################# 


# Color polygons with specific z range: 
# Create a function to generate a continuous color palette to work with 
rbPal <- colorRampPalette(c('red','white','blue')) 

# Make color scale for polygons 1 & 2 by cutting the continuous 
# palette object (rbPal) into 50 discrete blocks. 
# Each of these blocks will be defined by the polygon layer 
# values in a sequence ranging from 1 to 100 
head(poly1); summary(poly1) 
poly1$Col <- rbPal(50)[as.numeric(cut(poly1$layer, breaks = c(seq(1, 100, by=2))))] 
poly2$Col <- rbPal(50)[as.numeric(cut(poly2$layer, breaks = c(seq(1, 100, by=2))))] 
head(poly1); head(poly2) 

# Plot 
par(mfrow=c(1,2)) 
plot(poly1, col=poly1$Col) 
plot(poly2, col=poly2$Col)