Re: Masked arrays in PyNIO 1.3.0b1

Note to all: this was reposted to pyngl-talk, and responded to there.

--Mary

On Fri, 29 Aug 2008, Daran Rife wrote:

> Hi,
>
> I Recently installed the latest version of PyNIO 1.3.0b1
> for Mac OS X Leopard (Intel) running Python 2.5:
>
> PyNIO-1.3.0b1.macosx-10.5-i386-2.5.tar.gz
>
> I was excited to learn that when reading variables from
> netCDF files, Nio now returns a masked array for any var-
> iable having the _FillValue or missing_value attribute
> set within the input file.
>
> When I try this, Nio still seems to return a numpy.ndarray,
> instead of the desired masked array. Attached below is out-
> put from my IDLE session. Could someone please help me un-
> derstand what I am doing wrong?
>
> Also, are there examples showing how to properly set the
> new MaskedArrayMode options?
>
>
> Thanks in advance for your help,
>
>
> Daran
>
> --
>
> --->
>
> Python 2.5 (r25:51918, Sep 19 2006, 08:49:13)
> Type "copyright", "credits" or "license" for more information.
>
> IPython 0.8.4 -- An enhanced Interactive Python.
> ? -> Introduction and overview of IPython's features.
> %quickref -> Quick reference.
> help -> Python's own help system.
> object? -> Details about 'object'. ?object also works, ?? prints more.
>
> In [1]: import Nio as nio
>
> In [2]: f = nio.open_file('composite.20080523.L3m_DAY_SST_4.nc', 'r')
>
> In [3]: sst = f.variables['sst_data']
>
> In [4]: print sst
> Variable: sst_data
> Type: float
> Total Size: 3110400 bytes
> 777600 values
> Number of Dimensions: 3
> Dimensions and sizes: [time | 1] x [latitude | 720] x [longitude | 1080]
> Coordinates:
> time: [14022..14022]
> latitude: [24.52084..54.47918]
> longitude: [-98.47916..-53.52083]
> Number of Attributes: 5
> long_name : MODIS 8-day composite SST
> standard_name : sea_surface_temperature
> units : degC
> valid_range : [-1.979918837547302, 31.75502777099609]
> _FillValue : 1e+20
>
>
> In [5]: s = sst.get_value()
>
> In [6]: type(s)
> Out[6]: <type 'numpy.ndarray'>
>
> In [8]: from numpy import ma
>
> In [9]: s = ma.masked_values(sst.get_value(), sst._FillValue) # Force data
> into ma
>
> In [10]: type(s)
> Out[10]: <class 'numpy.ma.core.MaskedArray'>
>
> <---
>
>
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>
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Received on Sun Aug 31 2008 - 08:12:34 MDT