scipy中netcdf读写

>>>from scipy.io import netcdf

>>> help(netcdf)
Help on module scipy.io.netcdf in scipy.io:

NAME
scipy.io.netcdf - NetCDF reader/writer module.

FILE
/home/pan/.soft/epd/epd-7.3-2-rh5-x86/lib/python2.7/site-packages/scipy/io/netcdf.py

DESCRIPTION
This module is used to read and create NetCDF files. NetCDF files are
accessed through the `netcdf_file` object. Data written to and from NetCDF
files are contained in `netcdf_variable` objects. Attributes are given
as member variables of the `netcdf_file` and `netcdf_variable` objects.

Notes
-----
NetCDF files are a self-describing binary data format. The file contains
metadata that describes the dimensions and variables in the file. More
details about NetCDF files can be found `here
<http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html>`_. There
are three main sections to a NetCDF data structure:

1. Dimensions
2. Variables
3. Attributes

The dimensions section records the name and length of each dimension used
by the variables. The variables would then indicate which dimensions it
uses and any attributes such as data units, along with containing the data
values for the variable. It is good practice to include a
variable that is the same name as a dimension to provide the values for
that axes. Lastly, the attributes section would contain additional
information such as the name of the file creator or the instrument used to
collect the data.

When writing data to a NetCDF file, there is often the need to indicate the
'record dimension'. A record dimension is the unbounded dimension for a
variable. For example, a temperature variable may have dimensions of
latitude, longitude and time. If one wants to add more temperature data to
the NetCDF file as time progresses, then the temperature variable should
have the time dimension flagged as the record dimension.

This module implements the Scientific.IO.NetCDF API to read and create
NetCDF files. The same API is also used in the PyNIO and pynetcdf
modules, allowing these modules to be used interchangeably when working
with NetCDF files. The major advantage of this module over other
modules is that it doesn't require the code to be linked to the NetCDF
libraries.

In addition, the NetCDF file header contains the position of the data in
the file, so access can be done in an efficient manner without loading
unnecessary data into memory. It uses the ``mmap`` module to create
Numpy arrays mapped to the data on disk, for the same purpose.

Examples
--------
To create a NetCDF file:

>>> from scipy.io import netcdf
>>> f = netcdf.netcdf_file('simple.nc', 'w')
>>> f.history = 'Created for a test'
>>> f.createDimension('time', 10)
>>> time = f.createVariable('time', 'i', ('time',))
>>> time[:] = range(10)
>>> time.units = 'days since 2008-01-01'
>>> f.close()

Note the assignment of ``range(10)`` to ``time[:]``. Exposing the slice
of the time variable allows for the data to be set in the object, rather
than letting ``range(10)`` overwrite the ``time`` variable.

To read the NetCDF file we just created:

>>> from scipy.io import netcdf
>>> f = netcdf.netcdf_file('simple.nc', 'r')
>>> print f.history
Created for a test
>>> time = f.variables['time']
>>> print time.units
days since 2008-01-01
>>> print time.shape
(10,)
>>> print time[-1]
9
>>> f.close()

CLASSES
__builtin__.object
netcdf_file

class netcdf_file(__builtin__.object)
| A file object for NetCDF data.
|
| A `netcdf_file` object has two standard attributes: `dimensions` and
| `variables`. The values of both are dictionaries, mapping dimension
| names to their associated lengths and variable names to variables,
| respectively. Application programs should never modify these
| dictionaries.
|
| All other attributes correspond to global attributes defined in the
| NetCDF file. Global file attributes are created by assigning to an
| attribute of the `netcdf_file` object.
|
| Parameters
| ----------
| filename : string or file-like
| string -> filename
| mode : {'r', 'w'}, optional
| read-write mode, default is 'r'
| mmap : None or bool, optional
| Whether to mmap `filename` when reading. Default is True
| when `filename` is a file name, False when `filename` is a
| file-like object
| version : {1, 2}, optional
| version of netcdf to read / write, where 1 means *Classic
| format* and 2 means *64-bit offset format*. Default is 1. See
| `here <http://www.unidata.ucar.edu/software/netcdf/docs/netcdf/Which-Format.html>`_
| for more info.
|
| Methods defined here:
|
| __del__ = close(self)
|
| __init__(self, filename, mode='r', mmap=None, version=1)
| Initialize netcdf_file from fileobj (str or file-like).
|
| __setattr__(self, attr, value)
|
| close(self)
| Closes the NetCDF file.
|
| createDimension(self, name, length)
| Adds a dimension to the Dimension section of the NetCDF data structure.
|
| Note that this function merely adds a new dimension that the variables can
| reference. The values for the dimension, if desired, should be added as
| a variable using `createVariable`, referring to this dimension.
|
| Parameters
| ----------
| name : str
| Name of the dimension (Eg, 'lat' or 'time').
| length : int
| Length of the dimension.
|
| See Also
| --------
| createVariable
|
| createVariable(self, name, type, dimensions)
| Create an empty variable for the `netcdf_file` object, specifying its data
| type and the dimensions it uses.
|
| Parameters
| ----------
| name : str
| Name of the new variable.
| type : dtype or str
| Data type of the variable.
| dimensions : sequence of str
| List of the dimension names used by the variable, in the desired order.
|
| Returns
| -------
| variable : netcdf_variable
| The newly created ``netcdf_variable`` object.
| This object has also been added to the `netcdf_file` object as well.
|
| See Also
| --------
| createDimension
|
| Notes
| -----
| Any dimensions to be used by the variable should already exist in the
| NetCDF data structure or should be created by `createDimension` prior to
| creating the NetCDF variable.
|
| flush(self)
| Perform a sync-to-disk flush if the `netcdf_file` object is in write mode.
|
| See Also
| --------
| sync : Identical function
|
| sync = flush(self)
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)

DATA
__all__ = ['netcdf_file']