Adding initial version of fac_matrix_make

Currently only supports Xgse

pyspedas/cotrans/fac_matrix_make.py

@@ -0,0 +1,84 @@
+
+import logging
+import numpy as np
+
+from pyspedas.analysis.tnormalize import tnormalize
+from pyspedas.analysis.tcrossp import tcrossp
+
+from pytplot import get_data, store_data, options
+
+logging.captureWarnings(True)
+logging.basicConfig(format='%(asctime)s: %(message)s', datefmt='%d-%b-%y %H:%M:%S', level=logging.INFO)
+
+def xgse(mag_temp):
+    """
+    Generates the 'xgse' transformation matrix
+    """
+    mag_data = get_data(mag_temp)
+
+    # xaxis of this system is X of the gse system. Z is mag field
+    x_axis = np.zeros((len(mag_data.times), 3))
+    x_axis[:, 0] = 1
+
+    # create orthonormal basis set
+    z_basis = tnormalize(mag_temp, return_data=True)
+    y_basis = tcrossp(z_basis, x_axis, return_data=True)
+    y_basis = tnormalize(y_basis, return_data=True)
+    x_basis = tcrossp(y_basis, z_basis, return_data=True)
+
+    return (x_basis, y_basis, z_basis)
+
+
+def fac_matrix_make(mag_var_name, other_dim='Xgse', pos_var_name=None, newname=None):
+    """
+    Generates a field aligned coordinate transformation matrix
+    from an input B vector array(and sometimes a position vector array)
+    then stores it in a tplot variable
+
+    Input
+    ----------
+        mag_var_name: str
+            tplot variable containing the B-field data
+
+    Parameters
+    ----------
+        other_dim: str, optional
+            The second axis for the field aligned coordinate system (default: Xgse)
+
+        pos_var_name: str, optional
+            tplot variable containing the spacecraft position data
+
+        newname: str, optional
+            Name of the output tplot variable containing the FAC transformation matrices
+
+    Returns
+    ----------
+
+        Name of the tplot variable created.
+
+    """
+
+    mag_data = get_data(mag_var_name)
+
+    if mag_data is None:
+        logging.error('Error reading tplot variable: ' + mag_var_name)
+        return
+
+    if newname is None:
+        newname = mag_var_name + '_fac_mat'
+
+    other_dim = other_dim.lower()
+
+    if other_dim == 'xgse':
+        basis = xgse(mag_var_name)
+
+    fac_output = np.zeros((len(mag_data.times), 3, 3))
+    fac_output[:, 0, :] = basis[0]
+    fac_output[:, 1, :] = basis[1]
+    fac_output[:, 2, :] = basis[2]
+
+    store_data(newname, data={'x': mag_data.times, 'y': fac_output})
+
+    return newname
+
+