Package 'ffraster'

Title: Native Raster Files
Description: Provides a loose couplings between the facilities of `raster` and `ff`, to allow a file-backed raster grid to be modified as if it were an array in memory.
Authors: Michael D. Sumner [aut, cre]
Maintainer: Michael D. Sumner <[email protected]>
License: GPL-3
Version: 0.0.1.9001
Built: 2024-11-21 05:21:59 UTC
Source: https://github.com/hypertidy/ffraster

Help Index


dimension order

Description

The dimension order as used by ff and raster native grid, see 'raster::writeRaster'. The raster package uses the named conventions "BSQ", "BIL" and "BIP" which are domain-specialized ways to record the dimension order of (virtual) 3D arrays. They stand for "band sequential" "band interleaved" and ... correspond to c(1, 2, 3) etc. etc.

Usage

dim_order(x, ...)

## S3 method for class 'BasicRaster'
dim_order(x, ...)

## S3 method for class 'character'
dim_order(x, ...)

Arguments

x

filename or raster object or ff object

...

ignored

Details

This function always returns an integer vector indicating the order of the dims of a 'length(dim_order(x))' array oriented relative to the R array convention.

Value

integer vector of dimension positions (1-based)

Examples

r <- raster::raster(volcano)
dim_order(r)
w <- raster::writeRaster(r, raster::rasterTmpFile(), bandorder = "BIP")
dim_order(w)
dim_order(raster::filename(w))

Raster and 'ff' file-backed arrays

Description

Create an file-backed 'ff' object from a raster, or a raster-enabled file.

Usage

ff_object(x, readonly = TRUE, filename = NULL, ...)

## S3 method for class 'BasicRaster'
ff_object(x, readonly = TRUE, filename = NULL,
  ...)

## S3 method for class 'character'
ff_object(x, readonly = TRUE, filename = NULL, ...)

Arguments

x

raster or raster-able file

readonly

open in read-only mode (TRUE by default)

filename

path to file to create

...

arguments to methods

Details

When the object is created from a filename, ‘raster::brick' is used. The ’dim'ension for raster and for ff in this context always keeps degenerate singletons. Please get in touch if this causes you problems.

Value

'ff' object

Examples

f <- system.file("extdata", "raster", "sst.grd", package  = "ffraster")
ff_object(raster::brick(f))
if (interactive()) {
  arr <- ff_object(f, filename = "afile.grd")
 }

Create an ffraster

Description

Use a raster template to set up an ff array for filling.

Usage

ff_raster(x, nlayers = NULL, filename = NULL, ..., setZ = NULL)

Arguments

x

a raster object, used as the template for the data to come

nlayers

the number of layers to instantiate

filename

the .grd filename

...

arguments passed to .writeGRD

setZ

optional z values, must be of length 'nlayers'

Details

Note that no data is transferred, this is a set up function to give an ff array to be populated.

There is currently no control over the bandorder, set to band interleaved (BIL) currently.

Examples

## Not run: 
n <- 5
files <- raadtools::sstfiles()[1:n, ]

library(raster)
fun <- function(date) raadtools::readsst(date, xylim = extent(120, 160, -50, -30), inputfiles = files)
arr <- ff_raster(fun(files$date[1]), nlayers = n, filename = "afile.grd", overwrite = TRUE)
for (i in seq_along(files$date)) {
arr[,,i] <-   raster::values(t(fun(files$date[i])))
}
# plot(brick("afile.grd"))

## End(Not run)

ff type from raster type

Description

ff type from raster type

Usage

ff_type(x, ...)

## S3 method for class 'character'
ff_type(x, ...)

## S3 method for class 'BasicRaster'
ff_type(x, ...)

## S3 method for class 'raster_ini'
ff_type(x, ...)

Arguments

x

filename, raster object, or ini object

...

ignored

Value

type of ff, see 'ff::vmode'

Examples

ff_type("LOG1S")

ffraster

Description

Build a ff array to be used as a raster. For mapping between raster and ff types, see vmode and dataType

Usage

ffrarr(dim, mode, filename, readonly = TRUE)

Arguments

dim

dimensions in Raster order (nrow, ncol, nlayer)

mode

ff data mode see details

filename

file name as per writeRaster

readonly

open in readonly mode (TRUE is default)

Value

ff

Examples

mat <- volcano
library(raster)
b <- brick(raster(mat), raster(mat), raster(mat))
fn <- rasterTmpFile()
dt <- "byte"
ffraster:::.writeGRD(b, dataType = dt, filename = fn)
a <- ffrarr(dim(b), mode = dt, filename = fn, readonly = FALSE)

ffraster.

Description

ffraster.


raster ini file

Description

Read the configuration file in raw list form, you can use either the filename (.grd) or a raster object.

Usage

ini_file(x)

## S3 method for class 'character'
ini_file(x)

## S3 method for class 'BasicRaster'
ini_file(x)

Arguments

x

file name or raster

Examples

f <- system.file("extdata", "raster", "sst.grd", package  = "ffraster")
ini_file(f)