Basic GIS in R

Recently I had to help out a colleague with processing some spatial data in R. The overall goal was to find landscape parameters (topography, soil characteristics, etc.) within the neighbourhood of a flux tower.

The below  code gives a short introduction on how to extract data from both raster and shapefiles (vector data), very common operations .  I will add more tips and tricks as I come across them.

# Load libraries.
# For raster data

# For vector data

# Set flux tower coordinates.
lat= 45.2041

# Define lat / lon projection.
lat_lon <- CRS("+init=epsg:4326")

# Define UTM projection.
utm <- CRS( "+proj=utm +zone=19 +north +ellps=WGS84 +datum=WGS84 +no_defs")

# Read in the coordinates and assign them a projection, # otherwise they remain just 'numbers'
location <- SpatialPoints(cbind(lon,lat), lat_lon)

# Convert to utm using the above projection string
# using spTransform.
location_utm <- spTransform(location, utm)

# Load raster Digital Terrain Map (DTM) data.
# If the raster data has no projection,
# you will have to assign a projection.
# I assume the file has a projection.
dtm <- raster('DTM.tif')

# Relative height of the location of the tower.
dtm_data <- extract(dtm,location_utm)

# Read in soil shapefile.
soils <-  readShapeSpatial("soils.shp")

# Assign projection to the soils.shp file
# if not provided.
proj4string(soils) <- utm

# Extract soil polygon attributes.
soil_attributes <- over(location_utm,soils)


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