cdasws 0.1.1

Synopsis

This library provides a simple python interface to the data and services of NASA's Coordinated Data Analysis System (CDAS). This library implements the client side of the CDAS RESTful web services and returns data in the SpacePy data model with all the original ISTP/SPDF metadata. For more details about the CDAS web services, see https://cdaweb.sci.gsfc.nasa.gov/WebServices/REST/.

Code Example

The module contains example code call for most of the available web services. To run the included example, do the following

python -m cdasws

The following code demonstrates how to access magnetic field measurements from the ACE mission dataset

from cdasws import CdasWs

cdas = CdasWs()
data = cdas.get_data('AC_H1_MFI', ['Magnitude', 'BGSEc'],
                     '2009-06-01T00:00:00Z', '2009-06-01T00:10:00Z')[1]
print(data)
{'Epoch': VarCopy([datetime.datetime(2009, 6, 1, 0, 0),
     datetime.datetime(2009, 6, 1, 0, 4),
     datetime.datetime(2009, 6, 1, 0, 8)], dtype=object), 'Magnitude': VarCopy([3.495, 3.474, 3.477], dtype=float32), 'BGSEc': VarCopy([[-0.106,  2.521, -2.391],
     [-0.412,  2.402, -2.449],
     [-0.094,  2.309, -2.587]], dtype=float32), 'cartesian': VarCopy(['x_component', 'y_component', 'z_component'], dtype='<U11'), 'metavar0': VarCopy(['Bx GSE', 'By GSE', 'Bz GSE'], dtype='<U6')}

print(data['Magnitude'].attrs)

{'FIELDNAM': 'B-field magnitude', 'VALIDMIN': 0.0, 'VALIDMAX': 500.0, 'SCALEMIN': 0.0, 'SCALEMAX': 10.0, 'UNITS': 'nT', 'FORMAT': 'F8.3', 'VAR_TYPE': 'data', 'DICT_KEY': 'magnetic_field>magnitude', 'FILLVAL': -1e+31, 'DEPEND_0': 'Epoch', 'CATDESC': 'B-field magnitude', 'LABLAXIS': '<|B|>', 'DISPLAY_TYPE': 'time_series', 'DIM_SIZES': 0}

To have uniformly spaced (with respect to time) values computed, add the binData keyword paramter like this

status, data = cdas.get_data('AC_H1_MFI', ['Magnitude', 'BGSEc'],
                             '2009-06-01T00:00:00Z', '2009-06-01T00:10:00Z',
                             binData={
                                 'interval': 60.0,
                                 'interpolateMissingValues': True,
                                 'sigmaMultiplier': 4
                             })
print(data)

{'Epoch_bin': VarCopy([datetime.datetime(2009, 6, 1, 0, 0, 30),
     datetime.datetime(2009, 6, 1, 0, 1, 30),
     datetime.datetime(2009, 6, 1, 0, 2, 30),
     datetime.datetime(2009, 6, 1, 0, 3, 30),
     datetime.datetime(2009, 6, 1, 0, 4, 30),
     datetime.datetime(2009, 6, 1, 0, 5, 30),
     datetime.datetime(2009, 6, 1, 0, 6, 30),
     datetime.datetime(2009, 6, 1, 0, 7, 30),
     datetime.datetime(2009, 6, 1, 0, 8, 30),
     datetime.datetime(2009, 6, 1, 0, 9, 30)], dtype=object), 'Epoch': VarCopy([datetime.datetime(2009, 6, 1, 0, 0),
     datetime.datetime(2009, 6, 1, 0, 4),
     datetime.datetime(2009, 6, 1, 0, 8)], dtype=object), 'Magnitude': VarCopy([3.495  , 3.48975, 3.4845 , 3.47925, 3.474  , 3.47475, 3.4755 ,
     3.47625, 3.477  , 3.477  ], dtype=float32), 'BGSEc': VarCopy([[-0.106    ,  2.521    , -2.391    ],
     [-0.1825   ,  2.49125  , -2.4055   ],
     [-0.259    ,  2.4615   , -2.42     ],
     [-0.3355   ,  2.4317498, -2.4345   ],
     [-0.412    ,  2.402    , -2.449    ],
     [-0.3325   ,  2.3787498, -2.4835   ],
     [-0.253    ,  2.3555   , -2.518    ],
     [-0.1735   ,  2.33225  , -2.5524998],
     [-0.094    ,  2.309    , -2.587    ],
     [-0.094    ,  2.309    , -2.587    ]], dtype=float32), 'MAGNITUDE_NBIN': VarCopy([1., 0., 0., 0., 1., 0., 0., 0., 1., 0.], dtype=float32), 'MAGNITUDE_BIN_DELTA_MINUS_VAR': VarCopy([-1.e+31, -1.e+31, -1.e+31, -1.e+31, -1.e+31, -1.e+31, -1.e+31,
     -1.e+31, -1.e+31, -1.e+31], dtype=float32), 'MAGNITUDE_BIN_DELTA_PLUS_VAR': VarCopy([-1.e+31, -1.e+31, -1.e+31, -1.e+31, -1.e+31, -1.e+31, -1.e+31,
     -1.e+31, -1.e+31, -1.e+31], dtype=float32), 'BGSEC_NBIN': VarCopy([[ 1.,  1.,  1.],
     [-0., -0., -0.],
     [-0., -0., -0.],
     [-0., -0., -0.],
     [ 1.,  1.,  1.],
     [-0., -0., -0.],
     [-0., -0., -0.],
     [-0., -0., -0.],
     [ 1.,  1.,  1.],
     [-0., -0., -0.]], dtype=float32), 'BGSEC_BIN_DELTA_MINUS_VAR': VarCopy([[-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31]], dtype=float32), 'BGSEC_BIN_DELTA_PLUS_VAR': VarCopy([[-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31],
     [-1.e+31, -1.e+31, -1.e+31]], dtype=float32), 'cartesian_bin': VarCopy(['x_component', 'y_component', 'z_component'], dtype='<U11'), 'cartesian': VarCopy(['x_component', 'y_component', 'z_component'], dtype='<U11'), 'metavar0': VarCopy(['Bx GSE', 'By GSE', 'Bz GSE'], dtype='<U6'), 'metavar1': VarCopy(['# of Bx GSE', '# of By GSE', '# of Bz GSE'], dtype='<U11'), 'metavar2': VarCopy('# of ', dtype='<U5')}

Motivation

This library hides the HTTP, JSON/XML, and CDF details of the CDAS web services. A python developer only has to deal with python objects and methods (primarily the SpacePy data model object with full ISTP/SPDF metadata).

Dependencies

The primary dependency is SpacePy. Refer to the SpacePy documentation for the details of SpacePy's dependencies. In particular, this module depends upon the SpacePy data model's CDF import capability which is not automatically installed with SpacePy.

Installation

As noted in the dependencies above, you must install the CDF library by following the procedures at the CDF web site.

Then, to install this module

$ pip install cdasws

API Reference

Refer to cdasws module API reference

or use the standard python help mechanism.

from cdasws import CdasWs
help(CdasWs)

Tests

The tests directory contains unittest tests.

Contributors

Bernie Harris.
e-mail for support.

License

This code is licensed under the NASA Open Source Agreement (NOSA).