Not sure about the NetCDF-4 end but since your file is actually an HDF5 file,
you can use h5dump -H -p to dump the header and the compression info. for each
variable.
Search STORAGE_LAYOUT for the output file. You can see something like:
DATASET "Image_14" {
DATATYPE H5T_STD_U8LE
DATASPACE SIMPLE { ( 700, 1000, 3 ) / ( 700, 1000, 3 ) }
STORAGE_LAYOUT {
CHUNKED ( 700, 1000, 3 )
SIZE 72698 (28.887:1 COMPRESSION)
}
FILTERS {
PREPROCESSING SHUFFLE
COMPRESSION DEFLATE { LEVEL 1 }
}
That SIZE info. tells you the compression ratio. The filters tell you the
compression scheme you are using. Currently for NetCDF, only deflate and
shuffle are available.
Kent
-----Original Message-----
From: netcdfgroup-bounces@xxxxxxxxxxxxxxxx
[mailto:netcdfgroup-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Timothy Patterson
Sent: Monday, May 19, 2014 10:00 AM
To: netcdfgroup@xxxxxxxxxxxxxxxx
Subject: [netcdfgroup] Compressed sizes of netCDF variables
An example:
I have a netCDF file with 5 2-byte integer variables, each of dimensions 100 x
100 but containing different values. The data file on disk has a size of
(roughly) 100,000 bytes.
I then compress the variables individually using the in-built zip, and get file
size of 50,000 bytes. So my average compression across all the variables is a
factor of 2.
However, I'd like to monitor how well each individual variable has compressed.
Is there a way to determine the compressed size of a variable within the netCDF
file?
Thanks!
Tim Patterson
_______________________________________________
netcdfgroup mailing list
netcdfgroup@xxxxxxxxxxxxxxxx
For list information or to unsubscribe, visit:
http://www.unidata.ucar.edu/mailing_lists/
