# Copyright 2018 Regents of the University of Colorado. All Rights Reserved.
# Released under the MIT license.
# This software was developed at the University of Colorado's Laboratory for Atmospheric and Space Physics.
# Verify current version before use at: https://github.com/MAVENSDC/Pytplot
import pytplot
import numpy as np
import copy
import logging
[docs]
def derive(tvar,newname=None, new_tvar=None):
"""
Takes the derivative of the tplot variable.
Parameters
----------
tvar : str
Name of tplot variable.
new_tvar : str (Deprecated)
Name of new tplot variable. If not set, then the data in tvar is replaced.
newname : str
Name of new tplot variable. If not set, then the data in tvar is replaced.
Returns
-------
None
Examples
--------
>>> pyspedas.store_data('b', data={'x':[2,5,8,11,14,17,20], 'y':[[1,1,1,1,1,1],[2,2,5,4,1,1],[100,100,3,50,1,1],[4,4,8,58,1,1],[5,5,9,21,1,1],[6,6,2,2,1,1],[7,7,1,6,1,1]]})
>>> pyspedas.derive('b','dbdt')
"""
# new_tvar is deprecated in favor of newname
if new_tvar is not None:
logging.info("derive: The new_tvar parameter is deprecated. Please use newname instead.")
newname = new_tvar
a = pytplot.data_quants[tvar].differentiate('time')
if newname is None:
a.name = tvar
a.attrs = copy.deepcopy(pytplot.data_quants[tvar].attrs)
pytplot.data_quants[tvar] = a
else:
data = {'x':a.coords['time'], 'y':a.values * 1e09} # Internal time in units of nanoseconds
for coord in a.coords:
if coord != 'time' and coord != 'spec_bins':
data[coord] = a.coords[coord].values
pytplot.store_data(newname, data=data)
pytplot.data_quants[newname].attrs = copy.deepcopy(pytplot.data_quants[tvar].attrs)
return