def nrel_earthsun_distance(time, how='numpy', delta_t=67.0, numthreads=4):
"""
Calculates the distance from the earth to the sun using the
NREL SPA algorithm.
The details of the NREL SPA algorithm are described in [1]_.
Parameters
----------
time : pandas.DatetimeIndex
Must be localized or UTC will be assumed.
how : str, optional, default 'numpy'
Options are 'numpy' or 'numba'. If numba >= 0.17.0
is installed, how='numba' will compile the spa functions
to machine code and run them multithreaded.
delta_t : float, optional, default 67.0
If delta_t is None, uses spa.calculate_deltat
using time.year and time.month from pandas.DatetimeIndex.
For most simulations specifing delta_t is sufficient.
Difference between terrestrial time and UT1.
*Note: delta_t = None will break code using nrel_numba,
this will be fixed in a future version.*
By default, use USNO historical data and predictions
numthreads : int, optional, default 4
Number of threads to use if how == 'numba'.
Returns
-------
dist : pd.Series
Earth-sun distance in AU.
References
----------
.. [1] Reda, I., Andreas, A., 2003. Solar position algorithm for solar
radiation applications. Technical report: NREL/TP-560- 34302. Golden,
USA, http://www.nrel.gov.
"""
if not isinstance(time, pd.DatetimeIndex):
try:
time = pd.DatetimeIndex(time)
except (TypeError, ValueError):
time = pd.DatetimeIndex([time, ])
unixtime = np.array(time.astype(np.int64)/10**9)
spa = _spa_python_import(how)
delta_t = delta_t or spa.calculate_deltat(time.year, time.month)
dist = spa.earthsun_distance(unixtime, delta_t, numthreads)
dist = pd.Series(dist, index=time)
return dist
def nrel_earthsun_distance(time, how='numpy', delta_t=67.0, numthreads=4):
"""
Calculates the distance from the earth to the sun using the
NREL SPA algorithm described in [1].
Parameters
----------
time : pd.DatetimeIndex
how : str, optional
Options are 'numpy' or 'numba'. If numba >= 0.17.0
is installed, how='numba' will compile the spa functions
to machine code and run them multithreaded.
delta_t : float, optional
If delta_t is None, uses spa.calculate_deltat
using time.year and time.month from pandas.DatetimeIndex.
For most simulations specifing delta_t is sufficient.
Difference between terrestrial time and UT1.
*Note: delta_t = None will break code using nrel_numba,
this will be fixed in a future version.
By default, use USNO historical data and predictions
numthreads : int, optional
Number of threads to use if how == 'numba'.
Returns
-------
dist : pd.Series
Earth-sun distance in AU.
References
----------
[1] Reda, I., Andreas, A., 2003. Solar position algorithm for solar
radiation applications. Technical report: NREL/TP-560- 34302. Golden,
USA, http://www.nrel.gov.
"""
if not isinstance(time, pd.DatetimeIndex):
try:
time = pd.DatetimeIndex(time)
except (TypeError, ValueError):
time = pd.DatetimeIndex([time, ])
unixtime = np.array(time.astype(np.int64)/10**9)
spa = _spa_python_import(how)
delta_t = delta_t or spa.calculate_deltat(time.year, time.month)
dist = spa.earthsun_distance(unixtime, delta_t, numthreads)
dist = pd.Series(dist, index=time)
return dist
def nrel_earthsun_distance(time, how='numpy', delta_t=None, numthreads=4):
"""
Calculates the distance from the earth to the sun using the
NREL SPA algorithm described in [1].
Parameters
----------
time : pd.DatetimeIndex
how : str, optional
Options are 'numpy' or 'numba'. If numba >= 0.17.0
is installed, how='numba' will compile the spa functions
to machine code and run them multithreaded.
delta_t : float, optional
Difference between terrestrial time and UT1.
By default, use USNO historical data and predictions
numthreads : int, optional
Number of threads to use if how == 'numba'.
Returns
-------
R : pd.Series
Earth-sun distance in AU.
References
----------
[1] Reda, I., Andreas, A., 2003. Solar position algorithm for solar
radiation applications. Technical report: NREL/TP-560- 34302. Golden,
USA, http://www.nrel.gov.
"""
delta_t = delta_t or 67.0
if not isinstance(time, pd.DatetimeIndex):
try:
time = pd.DatetimeIndex(time)
except (TypeError, ValueError):
time = pd.DatetimeIndex([time, ])
unixtime = time.astype(np.int64)/10**9
spa = _spa_python_import(how)
R = spa.earthsun_distance(unixtime, delta_t, numthreads)
R = pd.Series(R, index=time)
return R