使用基於功能輸出的值創建柵格

Question

我有一個函數，可根據輸入斜率和距離計算價格。我想將價格寫入柵格作爲柵格值。我怎麼做？ OpenSource和ArcMap解決方案可以工作。

slopeRaster = "slope.tif" 
emptyRaster = "emptyraster.tif" # How do I create an empty raster? 
road = "road.shp" 

for cell in emptyraster: 
    # get slope from sloperaster at cell location 
    ... 
    slope = ... 

    # get distance to nearest road from center of cell 
    ... 
    distance = ... 

    # calculate price for cell 
    price = pricefunc(slope, distance) 

    # write price to cell as value # How do I write a value to a raster 

Answer 1

你可以很容易地在R中做到這一點。我建議你download and install it（它是免費的和開源的）。你唯一需要做的就是研究如何在R中編寫你的價格函數，這就是爲什麼我建議你發佈代碼。一旦你定義了pricefunc，你就可以從R命令行運行這些命令。

# Install required packages 
install.packages(c("raster" , "spatstat" , "sp" , "rgdal") , dep = TRUE) 

# Load required packages 
require(raster) 
require(spatstat) 
require(sp) 
require(rgdal) 

# Read in your data files (you might have to alter the directory paths here, the R default is to look in your $USERHOME$ directory R uses/not \ to delimit directories 
slp <- raster("slope.tif") 
roads <- readShapeLines("road.shp") 


# Create point segment pattern from Spatial Lines 
distPSP <- as.psp(roads) 


# Create point pattern from slope raster values 
slpPPP <- as.ppp(values(slp)) 


# Calculate distances from lines for each cell 
distances <- nncross(slpPPP , distPSP) 


# Create raster with calcualted distances 
rDist <- raster(slp) 
values(rDist) <- distances 


# Define your princefunc() here. It should take two input values, slope and distance and return one value, which I have called price 
pricefunc <- function(slp , dist){ 
    ...my code 
     ... more code 
    ...more code 
    return(price) 
} 


# Calculate price raster using your price function and save as output.tif 
rPrice <- overlay(slp , rDist , fun = function(x , y){ pricefunc(x , y) } , filename = "output.tif")