On Mon, Feb 9, 2015 at 10:22 AM, Signell, Richard <rsignell@xxxxxxxx> wrote:
> I encouraged Jules A to post this to stackoverflow and tag with
> "netcdf" and "python".
good point -- that is a better forum for this kind of question.
> 3) I want more stackoverflow points.
>
why didn't you say so? I'll go give you some upvotes ;-)
-Chris
> -Rich
>
> On Mon, Feb 9, 2015 at 1:05 PM, Chris Barker <chris.barker@xxxxxxxx>
> wrote:
> > Do you have a (hopefully small) sample netcdf file to share? That makes
> it a
> > lot easier to debug.
> >
> > Also -- I can't help myself, so here are suggestions for making your
> code
> > more "pythonic":
> >
> >
> >> from netCDF4 import Dataset;
> >>
> >> from netCDF4 import num2date;
> >
> >
> > no need for semi-colons! also, no biggie, but you can do:
> >
> > from netCDF4 import Dataset, num2date
> >
> >>
> >> filename = "C:/filename.nc"
> >>
> >> nc = Dataset(filename, 'r', Format='NETCDF4')
> >> print nc.variables
> >
> >
> >>
> >> print 'Variable List'
> >>
> >> for i in nc.variables:
> >> print [i, nc.variables[i].units, nc.variables[i].shape]
> >
> >
> > when you write a for loop like this, "i" gets assigned to the variable
> > objects, so you should be able to just do:
> >
> > for var in nc.variables:
> > print var, var.units, var.shape
> >
> >
> >>
> >> # get coordinates variables
> >>
> >> lats = nc.variables['latitude'][:]
> >> lons = nc.variables['longitude'][:]
> >>
> >> try:
> >>
> >> assert(nc.variables['latitude'].units == 'degrees_north')
> >> except:
> >> raise AttributeError('latitude units attribute not what was expected'
> >
> >
> > using an assert and caching it is odd, either simply:
> >
> > assert nc.variables['latitude'].units == 'degrees_north'
> >
> > or maybe:
> >
> > if nc.variables['latitude'].units != 'degrees_north':
> > raise AttributeError('latitude units attribute not what was
> expected'
> >
> >>
> >> sfc= nc.variables['Min_SFC'][:]
> >>
> >> times = nc.variables['time'][:]
> >>
> >>
> >> # convert time
> >>
> >> print "Converting Dates"
> >> units = nc.variables['time'].units
> >> dates = num2date (times[:], units=units, calendar='365_day')
> >>
> >> #print [dates.strftime('%Y%m%d%H') for date in dates]
> >>
> >>
> >> header = ['Latitude', 'Longitude']
> >>
> >>
> >> # append dates to header string
> >>
> >> for d in dates:
> >> print d
> >> header.append(d)
> >>
> >> # write to file
> >> import csv
> >>
> >> with open('Output.csv', 'wb') as csvFile:
> >>
> >> outputwriter = csv.writer(csvFile, delimiter=',')
> >> outputwriter.writerow(header)
> >> outputwriter.writerow(content)
> >
> >
> > here is your bug:
> >
> > "with" is a context manager -- the idea is that is handles closing teh
> > file, etc for you. It will do that when you leave the with block. In this
> > case, you don't sem to ahve anything in the with block at all --
> surprozed
> > there isn't an error., but it should be indented after the with:
> >
> > with open('Output.csv', 'wb') as csvFile:
> > outputwriter = csv.writer(csvFile, delimiter=',')
> > outputwriter.writerow(header)
> > outputwriter.writerow(content)
> >
> > when you fall off that indentation level the file will be closed.
> >
> > So you need ALL your writing code in that blcok, or you could not use
> with,
> > and simply do:
> >
> > csvFile = open('Output.csv', 'wb')
> > outputwriter = csv.writer(csvFile, delimiter=',')
> > outputwriter.writerow(header)
> > outputwriter.writerow(content)
> >
> > then close the file at the end of your script -- or do'nt bother, it will
> > get closed fine when the script ends.
> >
> >> def WriteContent(outputwriter, content):
> >>
> >> outputwriter.writerow(content)
> >>
> >> return
> >
> >
> > no sure what the point of this is, why not simple call:
> >
> > outputwriter.writerow(content)
> >
> > when you need it.
> >
> >> for l in lons:
> >> content =[lats[l], lons[l]]
> >> WriteContent(outputwriter, content)
> >
> >
> > this looks wrng too -- "for l in lons" will assign the longitudes to l
> each
> > time, not an index. IF you want to loop thorugh two sequences as once,
> you
> > can use zip()
> >
> > for lat, lon in zip(lats, lons):
> > outputwriter.writerow( [lat, lon] )
> >
> > though, in fact, this will probably work:
> >
> > for coords in zip(lats, lons):
> > outputwriter.writerow(coords )
> >
> > or, if you want to get really fancy, use s list comprehension:
> >
> > [outputwriter.writerow(coords) for coords in zip (lats, lons) ]
> >
> > HTH,
> >
> > -Chris
> >
> >
> > --
> >
> > Christopher Barker, Ph.D.
> > Oceanographer
> >
> > Emergency Response Division
> > NOAA/NOS/OR&R (206) 526-6959 voice
> > 7600 Sand Point Way NE (206) 526-6329 fax
> > Seattle, WA 98115 (206) 526-6317 main reception
> >
> > Chris.Barker@xxxxxxxx
> >
> > _______________________________________________
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>
>
>
> --
> Dr. Richard P. Signell (508) 457-2229
> USGS, 384 Woods Hole Rd.
> Woods Hole, MA 02543-1598
>
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
Chris.Barker@xxxxxxxx
