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Read a window from a GDAL source as a garry-oriented matrix.

gdal_read_window.Rd

Returns the window with row 1 = northernmost. Offsets are 0-based pixel coordinates. If nodata is supplied, matching cells (and any file-level NA) are rewritten to NaN and the result is numeric.

Usage

gdal_read_window(
  path,
  band,
  x_off,
  y_off,
  x_size,
  y_size,
  nodata = numeric(0),
  open_options = character(0),
  out = c("matrix", "raw_f32"),
  scale = numeric(0),
  offset = numeric(0),
  decim = NULL
)

Arguments

path

Path or VSI URL readable by GDAL.

band

1-based band index, or a vector of them for a multi-band read in one pass.

x_off, y_off, x_size, y_size

0-based pixel window.

nodata

Length-0 or length-1 sentinel to promote to NaN.

open_options

GDAL open options ("KEY=VALUE").

out

Output form: "matrix" (default) returns an R numeric result; "raw_f32" returns the pixels packed as a raw row-major f32 payload, avoiding a numeric copy when the result feeds a binary store or another process.

scale, offset

Length-0 (absent) or length-1 band affine: values become v * scale + offset after the nodata sentinel is promoted to NaN, so sentinels never scale.

decim

Optional decimating-read spec from .rio_direct_spec() (fx/fy integer decimation factors, x_off/y_off the source pixel origin of the target grid, resamp the RasterIO algorithm). When supplied the window arguments are read as TARGET-grid pixels and translated to the source window internally, so a caller chunked on the target grid needs no coordinate maths of its own.

Value

With out = "matrix": a numeric y_size x x_size matrix for a single band, or a (band, y, x) numeric array when band is a vector. With out = "raw_f32": a raw row-major f32 payload (band planes contiguous when band is a vector).