Extract WORLDCLIM data using R for a single country

问题

I want to extract world climate data for minimum and maximum temperature for only one country India using R and save it as a data set (to use with my own data-set that contains crop yields at the district level). I have gone through several posts and can see that this can be done easily in R, however the posts that I have tried to follow are a bit different in terms of the commands or sequences and I am getting confused. (https://gis.stackexchange.com/questions/259478/worldclim-data-na-for-my-coordinates, https://gis.stackexchange.com/questions/227585/using-r-to-extract-data-from-worldclim

What I have tried to use is as follows.

library(raster)
library(sp)
r<- getData('CMIP5', var='tmin', res=10, rcp=45, model='HE', year=70)
r <- r[[c(1,12)]]
values <- extract(r,points)
df <- cbind.data.frame(coordinates(points),values)
head(df)

However, I can run only the first two lines and the line values

<- extract(r,points) gives the error Error in (function (classes, fdef, mtable)  : 
  unable to find an inherited method for function ‘extract’ for signature ‘"RasterStack", "function"’

Any suggestions?

回答1:

Here is the solution for it

library(raster)
library(sp)
library(rgeos)
library(rgdal)
library(sf)

r<- getData('CMIP5', var='tmin', res=10, rcp=45, model='HE', year=70)

#Using Zonal statistics
poly <- shapefile("Provide_your_drive_name" e.g. "F:\\Kriging in R\\India Shape files\\2011_Dist.shp")
plot(poly)

#This will take considerable time
ex <- extract(r, poly, fun='mean', na.rm=TRUE, df=TRUE, weights = TRUE) 

write.csv(cbind(poly$DISTRICT,ex),"Worldclim.csv", row.names = F)

# using centroids
nc <- st_read(dsn="Provide_your_drive_name" e.g. "F:\\Kriging in R\\India Shape files", layer="2011_Dist")
# just view the attributes & first 6 attribute values of the data
head(nc)
sp_cent <- gCentroid(as(nc, "Spatial"), byid = TRUE)
values <- extract(r,sp_cent)

write.csv(cbind(as.data.frame(nc$DISTRICT),as.data.frame(values)),"Worldclim_centroids.csv", row.names = F)

来源：https://stackoverflow.com/questions/60316356/extract-worldclim-data-using-r-for-a-single-country

标签

extraction