Re: [netcdfgroup] Unexpectedly large netCDF4 files from python

• To: Val Schmidt <vschmidt@xxxxxxxxxxxx>, netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: Re: [netcdfgroup] Unexpectedly large netCDF4 files from python
• From: "dmh@xxxxxxxx" <dmh@xxxxxxxx>
• Date: Tue, 5 Apr 2016 13:31:57 -0600

BTW and out of curiosity, why are you using vlen rather than string?
=Dennis


On 4/5/2016 12:44 PM, Val Schmidt wrote:

Hello netcdf folks,

I’m testing some python code for writing sets of timestamps and variable length binary blobs to a netcdf file and the resulting file size is perplexing to me.

The following segment of python code creates a file with just two variables, “timestamp” and “data”, populates the first entry of the timestamp variable with a float and the corresponding first entry of the data variable with an array of 100 unsigned 8-bit integers. The total amount of data is 108 bytes.

But the resulting file is over 73 MB in size. Does anyone know why this might be so large and what I might be doing to cause it?

Thanks,

Val


from netCDF4 import Dataset
import numpy

f = Dataset('scratch/text3.nc','w')

dim = f.createDimension('timestamp_dim',None)
data_dim = f.createDimension('data_dim',None)

data_t = f.createVLType('u1','variable_data_t’)

timestamp = f.createVariable('timestamp','d','timestamp_dim')
data = f.createVariable('data',data_t,'data_dim’)

timestamp[0] = time.time()
data[0] = uint8( numpy.ones(1,100))

f.close()

------------------------------------------------------
Val Schmidt
CCOM/JHC
University of New Hampshire
Chase Ocean Engineering Lab
24 Colovos Road
Durham, NH 03824
e: vschmidt [AT] ccom.unh.edu <http://ccom.unh.edu>
m: 614.286.3726




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