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How do I crop raster data in R?
We can use the crop() function to crop a raster to the extent of another spatial object. To do this, we need to specify the raster to be cropped and the spatial object that will be used to crop the raster. R will use the extent of the spatial object as the cropping boundary.
What is the raster package in R?
The raster package has functions for creating, reading, manipulating, and writing raster data. The package provides, among other things, general raster data manipulation functions that can easily be used to develop more specific functions.
How to extract values from a raster in R?
There are a few ways to go about this task. As our plots are circular, we’ll use the extract function in R allows you to specify a circular buffer with a given radius around an x,y point location. Values for all pixels in the specified raster that fall within the circular buffer are extracted.
How to extract Insitu data from a raster?
Let’s say we have our insitu data in two separate .csv (comma separate value) files: SJER/VegetationData/D17_2013_vegStr.csv: contains our vegetation structure data for each plot. SJER/PlotCentroids/SJERPlotCentroids.csv: contains the plot centroid location information (x,y) where we measured trees.
How to extract the maximum value of a pixel in R?
Values for all pixels in the specified raster that fall within the circular buffer are extracted. In this case, we can tell R to extract the maximum value of all pixels using the fun=max argument.
How to extract CHM values from a raster?
We will then extract all CHM pixels that fall within the plot boundary to use to estimate tree height for that plot. When a circular buffer is applied to a raster, some pixels fall fully within the buffer but some are partially excluded. Values for all pixels in the specified raster that fall within the circular buffer are extracted.