classConnection: Connection of raster objects.

In ursa: Non-Interactive Spatial Tools for Raster Processing and Visualization

Connection of raster objects.

Description

Class ursaConnection is a part of class ursaRaster. It defines storage of raster images and manipulations with reading and writing.

Usage

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

## S3 method for class 'ursaConnection'
seek(con, where = NA, origin = "start", rw = "", ...)

Arguments

x	ursaConnection object in function print.
con	ursaConnection object in function seek.
where	Passed to seek for class connection.
origin	Passed to seek for class connection.
rw	Passed to seek for class connection.
...	print: Further arguments passed to generic functions print and str. seek: Further arguments passed to function seek for class connection.

Details

ursaConnection get item $con from ursaRaster object.

Functions print and is.con are for developers rather than users.

Non-public function .con.skeleton() is used to generate the blank ursaConnection object. This approach provides unified sequence of list's items:

Value

ursaConnection is a list. The most of names have a relation to specification of ENVI Header Files. Items:

driver	Character. Keyword of supported image formats. Allowed "ENVI" or "GDAL".
samples	Integer. Number of image columns (samples)
lines	Integer. Number of image rows (lines)
bands	Integer. Number of image bands (channels, layers)
datatype	Integer. Keyword for data type (4 - 32-bit floating point, 2 - 16-bit signed integer, etc)
interleave	Character "bsq", "bil", "bip". Data interleave - streams of bytes in storage.
byteorder	Integer, 0 or 1. The order of bytes. byteorder=0 less significant byte first, byteorder=1 most significant byte first
endian	Character. See ⁠\dQuote{endian}⁠ argument in readBin and writeBin
swap	Integer 0 or 1. Passed to C-funcions fread and fwrite
signed	Logical. Derived from $datatype
offset	Integer. Header offset in binary file. Default is 0.
wkt	Logical. In ENVI Header files wkt=TRUE forced to use “coordinate system string” field instead of “projection info” field
nodata	Numeric. Replacement NA values in the storage.
mode	Character. storage.mode of data
sizeof	Integer, positive. Size in bytes for stored values. Extracted from $datatype
indexC	Integer vector. Sample indices in spatial cropping.
indexR	Integer vector. Line indices in spatial cropping.
indexZ	Integer vector. Band indices
posC	Integer vector. Sample indices in partial reading.
posR	Integer vector. Line indices in partial reading.
posZ	Integer vector. Band indices in spatial crottping or partial reading.
fname	Character. File name. If driver=ENVI, then full path for ENVI binary file.
connection	Character. See connections
compress	Signed integer. 0L no compressing, -1L comressed file plus decompressed file,-2L decompressed file, 1L - file will be compressed.
seek	Logical. Does connection support seek?
handle	connections in fact

Author(s)

Nikita Platonov [e-mail]

See Also

ursa(obj,"con")

Examples

session_grid(NULL)
print(methods(class="ursaConnection"))

a <- pixelsize()
write_envi(rep(a,5),"tmp1",compress=FALSE)
## change spatial domain for cropping example
g <- session_grid(regrid(lim=c(-1200000,-1400000,1600000,1800000)))
print(g)
b <- open_envi("tmp1")
d <- b[,30:70]
print(ursa(d[2:3],"con"))
close(b)
envi_remove("tmp1")

ursa documentation built on Sept. 30, 2024, 9:35 a.m.