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rrastertiff

How to extract information based on shapefile from dataframe?

I have a dataframe

lon lat year        U       CP     PS     FR     NT
1:  87  46 1650     0        0   0.198      0   0.802
2:  87  46 1651     0        0   0.197      0   0.803
3:  87  46 1652     0        0   0.195      0   0.805
4:  87  46 1653     0        0   0.193      0   0.807
5:  87  46 1654     0        0   0.192      0   0.808
6:  87  46 1655     0        0   0.190      0   0.810

I have dataframe that covers lon and lat globally. I would like to extract information according to my shape file. I donot know how can I make a reproducible example of raster showing global data. But I have made snippet show longitude and latitude.

Solution

  • Here is how you can make a global raster

    library(raster)
r <- raster()
values(r) <- 1:ncell(r)

    You can then extract values for point locations like this

    lonlat <- cbind(c(87, 86), c(46, 47))
extract(r, lonlat)
[1] 16108 15747