terra (version 1.0-10)

read and write: Read from, or write to, file

Description

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. When writing is done close the file with writeStop.

Usage

# 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, wopt=list(), ...)

# S4 method for SpatRaster writeStop(x)

# S4 method for SpatRaster,vector writeValues(x, v, start, nrows, ...)

Arguments

x

SpatRaster

filename

Character. Output filename. Optional

v

vector with cell values to be written

start

integer. Row number (counting starts at 1) from where to start writing v

row

positive integer. Row number to start from, should be between 1 and nrow(x)

nrows

positive integer. How many rows?

col

positive integer. Column number to start from, should be between 1 and ncol(x)

ncols

positive integer. How many columns? Default is the number of columns left after the start column

mat

logical. If TRUE, values are returned as a matrix instead of as a vector, except when dataframe is TRUE

dataframe

logical. If TRUE, values are returned as a data.frame instead of as a vector (also if matrix is TRUE)

overwrite

logical. If TRUE, filename is overwritten

wopt

list. Options for writing files as in writeRaster

...

additional arguments. None implemented

Value

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 succesful or not. Their purpose is the side-effect of opening or closing files.