compression.gdsn: Modify compression mode

Description Usage Arguments Details Value Author(s) References See Also Examples

View source: R/gdsfmt-main.r

Description

Modifie the compression mode of data field in the GDS node.

Usage

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compression.gdsn(node,
    compress=c("", "ZIP", "ZIP_RA", "LZMA", "LZMA_RA", "LZ4", "LZ4_RA"))

Arguments

node

an object of class gdsn.class, a GDS node

compress

the compression method can be "" (no compression), "ZIP", "ZIP.fast", "ZIP.def", "ZIP.max" or "ZIP.none" (original zlib); "ZIP_RA", "ZIP_RA.fast", "ZIP_RA.def", "ZIP_RA.max" or "ZIP_RA.none" (zlib with efficient random access); "LZ4", "LZ4.none", "LZ4.fast", "LZ4.hc" or "LZ4.max" (LZ4 compression/decompression library); "LZ4_RA", "LZ4_RA.none", "LZ4_RA.fast", "LZ4_RA.hc" or "LZ4_RA.max" (with efficient random access). "LZMA", "LZMA.fast", "LZMA.def", "LZMA.max", "LZMA_RA", "LZMA_RA.fast", "LZMA_RA.def", "LZMA_RA.max" (lzma compression/decompression algorithm). See details

Details

Z compression algorithm (http://www.zlib.net/) can be used to deflate the data stored in the GDS file. "ZIP" option is equivalent to "ZIP.def". "ZIP.fast", "ZIP.def" and "ZIP.max" correspond to different compression levels.

To support efficient random access of Z stream, "ZIP_RA", "ZIP_RA.fast", "ZIP_RA.def" or "ZIP_RA.max" should be specified. "ZIP_RA" option is equivalent to "ZIP_RA.def:256K". The block size can be specified by following colon, and "16K", "32K", "64K", "128K", "256K", "512K", "1M", "2M", "4M" and "8M" are allowed, like "ZIP_RA:64K". The compression algorithm tries to keep each independent compressed data block to be about of the specified block size, like 64K.

LZ4 fast lossless compression algorithm is allowed when compress="LZ4" (http://code.google.com/p/lz4/). Three compression levels can be specified, "LZ4.fast" (LZ4 fast mode), "LZ4.hc" (LZ4 high compression mode), "LZ4.max" (maximize the compression ratio). The block size can be specified by following colon, and "64K", "256K", "1M" and "4M" are allowed according to LZ4 frame format. "LZ4" is equivalent to "LZ4.hc:256K".

To support efficient random access of LZ4 stream, "LZ4_RA", "LZ4_RA.fast", "LZ4_RA.hc" or "ZIP_RA.max" should be specified. "LZ4_RA" option is equivalent to "LZ4_RA.hc:256K". The block size can be specified by following colon, and "16K", "32K", "64K", "128K", "256K", "512K", "1M", "2M", "4M" and "8M" are allowed, like "LZ4_RA:64K". The compression algorithm tries to keep each independent compressed data block to be about of the specified block size, like 64K.

LZMA compression algorithm (http://tukaani.org/xz/) is available since gdsfmt_v1.7.18, which has a higher compression ratio than ZIP algorithm. "LZMA", "LZMA.fast", "LZMA.def" and "LZMA.max" available. To support efficient random access of LZMA stream, "LZMA_RA", "LZMA_RA.fast", "LZMA_RA.def" and "LZMA_RA.max" can be used. The block size can be specified by following colon. "LZMA_RA" is equivalent to "LZMA_RA.def:256K".

compression 1 compression 2 command line
ZIP ZIP_RA gzip -6
ZIP.fast ZIP_RA.fast gzip --fast
ZIP.def ZIP_RA.def gzip -6
ZIP.max ZIP_RA.max gzip --best
LZ4 LZ4_RA LZ4 HC -6
LZ4.min LZ4_RA.min LZ4 fast 0
LZ4.fast LZ4_RA.fast LZ4 fast 2
LZ4.hc LZ4_RA.hc LZ4 HC -6
LZ4.max LZ4_RA.max LZ4 HC -9
LZMA LZMA_RA xz -6
LZMA.min LZMA_RA.min xz -0
LZMA.fast LZMA_RA.fast xz -2
LZMA.def LZMA_RA.def xz -6
LZMA.max LZMA_RA.max xz -9e
LZMA.ultra LZMA_RA.ultra xz --lzma2=dict=512Mi
LZMA.ultra_max LZMA_RA.ultra_max xz --lzma2=dict=1536Mi

Value

Return node.

Author(s)

Xiuwen Zheng

References

http://github.com/zhengxwen/gdsfmt, http://zlib.net/

See Also

readmode.gdsn, add.gdsn

Examples

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# cteate a GDS file
f <- createfn.gds("test.gds")

n <- add.gdsn(f, "int.matrix", matrix(1:50*100, nrow=100, ncol=50))
n

compression.gdsn(n, "ZIP")

# close the GDS file
closefn.gds(f)

# delete the temporary file
unlink("test.gds", force=TRUE)

gdsfmt documentation built on Dec. 26, 2020, 6 p.m.