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[python #MBM-874792]: NetCDF viewer recommendation

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  • Subject: [python #MBM-874792]: NetCDF viewer recommendation
  • Date: Fri, 13 Aug 2021 17:41:47 -0600
Greetings!

That math can definitely be tricky, which is why cftime is so handy:

    import cftime
    dt = cftime.num2date(738004.5, 'days since 1-1-1 00:00:0.0')
    print(dt)

gives "2021-08-01 12:00:00". `num2date` also supports being given an entire 
array of times that you get from the file, and you can avoid hard-coding the 
units with:

    import cftime
    from netCDF4 import Dataset

    nc = 
Dataset('http://nomads.ncep.noaa.gov:80/dods/gfs_0p25/gfs20210802/gfs_0p25_00z')
    time_var = nc.variables['time']
    time_vals = cftime.num2date(time_var[:], time_var.units)

Hope this helps!

Ryan

> One other note on this subject netcdf time.
> 
> I guess I got to learn to use cftime to convert my netcdf to units that make 
> sense. Looking at the GRADS server I finally understand what the unites mean
> and also what my numbers I see are for.
> 
> My start time unit is 738004.5, which was my start unit for Aug 1, 2021.
> 
> I did the math below. I got close enough, so I'm missing a leap day her or 
> there, but getting close.
> 
> Don't need to read below, but do you have an example of using cftime to 
> convert number of days since the beginning of time
> to our datetime object?
> 


Ticket Details
===================
Ticket ID: MBM-874792
Department: Support Python
Priority: Low
Status: Closed
===================
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