It is assumed that these files follow, or are compatible with, the CF-1 convention (The GMT format may also work). To use NetCDF files the ncdf4 package needs to be available. Let’s examine another image that may require more colors, but less detail. to create a RasterBrick of weather over time at a certain height. The default evectorize parameter will reduce it to a detail level of 300 pixels and 10 colors, which is quite sufficient for this image. To select the 'level' (4th dimension variable) to use, if the file has 4 dimensions, e.g. To select the 'level variable' (3rd dimension variable) to use, if the file has 4 dimensions (e.g. If not supplied and the file has multiple variables are a guess will be made (and reported) The variable name, such as 'tasmax' or 'pr'. If x represents a NetCDF file, the following additional variable is recognized: Ignored when the file provides a CRS description that can be interpreted. To indicate the number of header rows on non-standard ascii files (rarely useful use with caution)Ĭrs: character. The default is TRUE, in which case a raster attribute table is created for files that have one 'raster' and netcdf format files are always read with native drivers. If TRUE, reading and writing of IDRISI, BIL, BSQ, BIP, SAGA, and Arc ASCII files is done with native (raster package) drivers, rather then via rgdal. Default is FALSE except when package rgdal is missing. Subdataset number for a file with subdatasets If x is a filename, the following additional variables are recognized: If not NULL, arguments xmn, xmx, ymn, ymx and crs (unless template is an Extent object) are ignored Value Raster* or Extent object used to set the extent (and CRS in case of a Raster* object). You can assign new values with setValues and with replacement.įor an overview of the functions in the raster package have a look here: raster-package. You can access cell-values with getValues, extract and related functions. when a RasterLayer is created from a file, it does (initially) not contain any cell (pixel) values in (RAM) memory, it only has the parameters that describe the RasterLayer. RasterLayer objects can be created from scratch, a file, an Extent object, a matrix, an 'image' object, or from a Raster*, Spatial*, im (spatstat) asc, kasc (adehabitat*), grf (geoR) or kde object. Raster: Create a RasterLayer object Description

Convert raster to vector in r