Package 'gdalio'

Read GDAL raster numeric data

Description

Data may be one band (the default, first band) or many.

Usage

gdalio_graphics(dsn, bands = 1:3, ...)

gdalio_matrix(dsn, ...)

gdalio_array(dsn, ...)

gdalio_image(dsn, ..., extent = NULL, dimension = NULL, projection = NULL)

gdalio_data(dsn, ..., bands = 1L)

gdalio_graphics(dsn, bands = 1:3, ...)

gdalio_matrix(dsn, ...)

gdalio_array(dsn, ...)

Arguments

dsn	character string, raster source understood by GDAL
bands	default 1L, but can be more, duplicated in different order, or 'NULL' for all
...	arguments passed to 'vapour::vapour_warp_raster'

Details

gdalio_data() returns a list of vectors, gdalio_matrix() and gdalio_array() and gdalio_graphics() return a matrix, array, matrix of the necessary shape, as used by image() and plot().

The matrix of hex values returned by gdalio_graphics() cannot really be placed on a spatial plot window without a lot of extra work, but it's good for fast visuals to 'plot()' the output. We can write helpers to plot this thing better but WIP atm.

Value

list of numeric vectors

Examples

## Not run: 
 f <- system.file("extdata/sst.tif", package = "vapour", mustWork = TRUE)

 g <- list(extent = c(130, 160, -60, -30), dimension = c(180, 100),
    projection = "+proj=longlat")
 gdalio_set_default_grid(g)
 v <- gdalio_data(f, band_output_type = "int")
 image(seq(130, 160, length.out = 181), seq(-60, -30, length.out = 101),
    matrix(v[[1]], g$dimension[1])[,g$dimension[2]:1], asp = 1.5)

## End(Not run)

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Read GDAL raster data as RGB triples or hex colours

Description

gdalio_data_hex and gdalio_data_rgb are a little strange in that they return a vector of character strings and a list of numeric values respectively.

Usage

gdalio_data_rgb(dsn, bands = 1:3, ...)

gdalio_data_hex(dsn, bands = 1:3, ...)

Arguments

dsn	character string, raster source understood by GDAL
bands	bands to read, assumes 1:3 (can be 1:4 or any ordering)
...	arguments passed to 'vapour::vapour_warp_raster'

Value

'gdalio_data_rgb()' a list of integer vectors, 'gdalio_data_hex()' a character vector of "#" colours

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Print the code to source format-specific functions

Description

You can 'source()' the file path displayed by this function to define package-specific formats for the gdalio data.

Usage

gdalio_format_source()

Details

Running the code in the file path displayed by this function will load functions for terra, stars, raster, and spatstat.

Examples

## Not run: 
source(gdalio_format_source())

## End(Not run)

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Title

Description

Title

Usage

gdalio_get_default_grid()

Value

grid specification (list of extent, dimension, projection)

Examples

gdalio_get_default_grid()
gdalio_set_default_grid(list(extent = c(-1000, 1000, -2000, 2000),
 dimension = c(100, 200), projection = "+proj=longlat"))
gdalio_get_default_grid()

gdalio_set_default_grid()

---

Generate a local grid

Description

Generate a default local grid to use for subsequent data reads.

Usage

gdalio_local_grid(
  x = 147,
  y = -42,
  buffer = 2500000,
  family = "laea",
  dim = if (dev.cur() == 1) {
     c(512, 512)
 } else {
     dev.size("px")
 }
)

Arguments

x	longitude
y	latitude
buffer	width either side of x, y
family	projection family (as per PROJ strings)
dim	size of grid nx, ny

Details

All arguments have default values.

Value

list appropriate for gdalio_set_default_grid()

Examples

gdalio_local_grid()
gdalio_local_grid(family = "stere")

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Title

Description

Input may be a list with extent ⁠$dimension⁠, ⁠$projection⁠, which is c(xmin, xmax, ymin, ymax), c(ncol, nrow), and string (accepted by GDAL as a projection input). Alternatively, use a raster, stars, or terra object. Only simple cases of stars will work (regular grids with positive x, negative y transforms).

Usage

gdalio_set_default_grid(
  x,
  ...,
  extent = NULL,
  dimension = NULL,
  projection = NULL
)

Arguments

x	grid specification, a list with '$extent, $dimension, $projection' or a spatial grid object see Details

Value

the grid specification (originally: nothing, used to set a default grid available globally)

Examples

gdalio_set_default_grid(list(extent = c(-1000, 1000, -2000, 2000),
   dimension = c(100, 200), projection = "+proj=longlat"))
gdalio_set_default_grid()

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Data sources for reading

Description

Provides a data frame of online-accessible data sources. This is very incomplete and has no guarantee of success. It's your responsibility to check usage terms.

Usage

gdalio_sources()

Details

There is a table of sources 'provider', 'name', 'source' - source is a DSN in GDAL terms, you can query and read from it with GDAL.

Examples

srcs <- gdalio_sources()
ttsa <- subset(srcs, provider == "tasmap" & name == "TTSA")$source
ve <- subset(srcs, provider == "gdaltms" & name == "wms_virtualearth_street")$source
gdalio_set_default_grid(list(extent = c(-1, 1, -1, 1) * 800,
                             dimension = rep(min(dev.size("px")), 2L),
                             projection = "+proj=laea +lat_0=-42.8826 +lon_0=147.3257"))
source(gdalio_format_source())
tas_street <- gdalio_terra(ttsa, bands = 1:3, resample = "cubic")
ve_street <- gdalio_terra(ve, bands = 1:3, resample = "cubic")
par(mfrow = c(1, 2))
terra::plotRGB(tas_street)
terra::plotRGB(ve_street)

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Example data files

Description

Return a path to a data raster file, for easy access to examples.

Usage

gdalio_eg_raster()

gdalio_eg_image()

Details

This raster has sea surface temperature values in Celsius, with no colour palette defined.

Examples

gdalio_eg_raster()
gdalio_eg_image()

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sources

Description

sources

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Fix missing raster metadata

Description

Simple metadata augmentation for raster sources.

Usage

vrt(x, extent = NULL, projection = NULL)

## Default S3 method:
vrt(x, extent = NULL, projection = NULL)

Arguments

x	character string, file, url, GDAL dsn
extent	numeric 'c(xmin, xmax, ymin, ymax)'
projection	character wkt, proj, epsg code

Details

Simple function to add either or both of a raster source extent and projection string.

The attributes from 'extent' as 'source_extent' and/or 'projection' as 'source_projection' are passed directly down to GDAL, via the gdalio_data() function, which hands them on to vapour::vapour_warp_raster() arguments 'source_extent' and 'source_wkt' respectively.

Value

lightly classed character vector, with "vrt_simple", "character"

Examples

vrt("myfile.nc")
vrt("myfile.nc", extent = c(-180, 180, -90, 90))
str(vrt("myfile.nc", extent = c(-180, 180, -90, 90), projection = 4326))

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