[Numpy-discussion] Reading a big netcdf file

Christopher Barker Chris.Barker@noaa....
Wed Aug 3 13:38:08 CDT 2011

On 8/3/11 11:09 AM, Ian Stokes-Rees wrote:
> On 8/3/11 12:50 PM, Christopher Barker wrote:
>> As a reference, reading that much data in from a raw file into a numpy
>> array takes 2.57 on my machine (a rather old Mac, but disks haven't
>> gotten much faster).
> 2.57 seconds? or minutes?

sorry -- seconds.

>If seconds, does it actually read the whole
> thing into memory in that time, or is there some kind of delayed read
> going on?

I think it reads it all in. However, now that you bring it up, I think 
"timeit" does it a few times, and after the first time, there may well 
be disk cache that speeds things up.

In fact, as I recently wrote the file, there may be disk cache issues 
even on the first read.

I'm no timing expert, but there must be ways to get a clean time.


Christopher Barker, Ph.D.

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