Methods to read from or write chunks of values to or from a file. These are low level methods for programmers. Use writeRaster if you want to save an entire SpatRaster to file in one step. It is much easier to use.
To write chunks, begin by opening a file with
writeStart, then write values to it in chunks using the list that is returned by
writeStart. When writing is done, close the file with
blocks only returns chunk size information. This can be useful when reading, but not writing, raster data.
# S4 method for SpatRaster readStart(x) # S4 method for SpatRaster readStop(x) # S4 method for SpatRaster readValues(x, row=1, nrows=nrow(x), col=1, ncols=ncol(x), mat=FALSE, dataframe=FALSE, ...) # S4 method for SpatRaster,character writeStart(x, filename="", overwrite=FALSE, n=4, sources="", ...) # S4 method for SpatRaster writeStop(x) # S4 method for SpatRaster,vector writeValues(x, v, start, nrows) # S4 method for SpatRaster blocks(x, n=4) fileBlocksize(x)
character. Output filename
vector with cell values to be written
integer. Row number (counting starts at 1) from where to start writing
positive integer. Row number to start from, should be between 1 and nrow(x)
positive integer. How many rows?
positive integer. Column number to start from, should be between 1 and ncol(x)
positive integer. How many columns? Default is the number of columns left after the start column
TRUE, values are returned as a numeric matrix instead of as a vector, except when
dataframe=TRUE. If any of the layers of
x is a factor, the level index is returned, not the label. Use
dataframe=TRUE to get the labels
TRUE, values are returned as a
data.frame instead of as a vector (also if matrix is
filename is overwritten
positive integer indicating how many copies the data may be in memory at any point in time. This is used to determine how many blocks (large) datasets need to be read
character. Filenames that may not be overwritten because they are used as input to the function. Can be obtained with
writeStart: additional arguments for writing files as in
readValues: additional arguments for
data.frame (and thus only relevant when
readValues returns a vector, matrix, or data.frame
writeStart returns a list that can be used for processing the file in chunks.
The other methods invisibly return a logical value indicating whether they were successful or not. Their purpose is the side-effect of opening or closing files.