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Open a large spectral source as file-backed Specs

Source: R/Specs_file.R, R/Specs_methods.R
open_specs.Rd

FileSpecs keeps a durable, read-only description of a large H5 or ENVI source. Spectral values are read only when an explicit bounded selection is materialized. The object never stores an open connection or modifies a source member.

Usage

open_specs(path, cache_dir = NULL)

# S3 method for class 'FileSpecs'
as_Specs(x, ...)

# S3 method for class 'FileSpecs'
print(x, ...)

# S3 method for class 'FileSpecs'
check_Specs(x, ...)

# S3 method for class 'FileSpecs'
decompress_spec(x, index = NULL, region = NULL, roi = NULL, bands = NULL, ...)

# S3 method for class 'FileSpecs'
split_spec(x, by = "region", ...)

# S3 method for class 'FileSpecs'
cor_spec(x, ...)

# S3 method for class 'FileSpecs'
match_spec(x, ...)

# S3 method for class 'FileSpecs'
def_features(x, ...)

# S3 method for class 'FileSpecs'
collapse_spec(x, ...)

Arguments

path

path to an H5 file, an ENVI binary file, or its .hdr file.

cache_dir

directory for immutable derived cache generations. The default uses the user cache directory, never the source directory.

x

a FileSpecs object.

...

additional arguments reserved for methods.

index

positive row positions in the current file-backed view.

region

optional region names to materialize.

roi

optional numeric c(xmin, xmax, ymin, ymax) selection or a list with two-element x and y ranges.

bands

optional positive spectral-band positions to materialize.

by

grouping field; file-backed splitting currently supports only "region".

Value

open_specs() returns a descriptor-only FileSpecs object. decompress_spec() returns a bounded OpenSpecy materialization and split_spec() returns lightweight FileSpecs views.