pyacs.vel_field

Velocity field package: read, manipulate and write GMT psvelo velocity fields.

class pyacs.vel_field.Velocity_Field(file_name=None, name=None, lgmt_points=None, verbose=False)[source]

Bases: object

Read a velocity field from a GMT psvelo file and manipulate it.

name

Name of the velocity field.

Type:

str, optional

file_name

Path to the GMT psvelo file.

Type:

str, optional

sites

List of GMT_Point instances.

Type:

list

add_point(M)

Append a GMT_Point to the velocity field.

Parameters:

M (GMT_Point) – Point to add.

Returns:

self (for chaining).

Return type:

Velocity_Field

calc_pole(plates, method='WLS', verbose=False)

Perform Euler pole calculation for multiple plates.

Parameters:

  • plates (dict) – Plate name -> list of site codes for each plate.

  • method (str, optional) – ‘WLS’ (weighted least-squares) or ‘L1’. Default is ‘WLS’.

  • verbose (bool, optional) – If True, print progress. Default is False.

Notes

For each plate, creates: euler_stat_<plate>.dat, <plate>.gmt, <plate>.shp, and euler_sum.dat with Euler pole summary.

common(linGpoint, prefit=10.0, lexclude=[])

Return sites common to this velocity field and a list of GMT_Points.

Parameters:

  • linGpoint (list) – List of GMT_Point instances (e.g. from SINEX).

  • prefit (float, optional) – Maximum coordinate difference (m) to consider a match. Default is 10.0.

  • lexclude (list, optional) – Site codes to exclude.

Returns:

GMT_Point instances from this field that match by code (coordinates from this field).

Return type:

list

info(details=True)

Print basic information about the velocity field.

Parameters:

details (bool, optional) – If True, list all site codes. Default is True.

l_GMT_Point()

Return the velocity field as a list of GMT_Point objects.

Returns:

List of GMT_Point instances.

Return type:

list

lcode()

Return a list of all point codes in the velocity field.

Returns:

List of 4-character site codes.

Return type:

list

nsites()

Return the number of sites in the velocity field.

Returns:

Number of sites.

Return type:

int

pole(lexclude=[], method='WLS', exp='pLate', log=None)

Compute Euler pole from the velocity field.

Parameters:

  • lexclude (list, optional) – Site codes to exclude from the fit.

  • method (str, optional) – ‘WLS’ (weighted least squares), ‘LS’, or ‘Dikin’ (L1). Default is ‘WLS’.

  • exp (str, optional) – Experiment name prefix. Default is ‘pLate’.

  • log (str, optional) – Log file path. If None, uses exp + ‘.log’.

Returns:

(X, VCV_POLE_X): rotation rate vector (3,) and variance-covariance (3, 3).

Return type:

tuple

print_info_site(code, verbose=False)

Print information for a site given its code.

Parameters:

  • code (str) – 4-character site code.

  • verbose (bool, optional) – If True, print legend. Default is False.

proj_profile(slon, slat, elon, elat, d, save=None, verbose=False)

Project velocity components along a great-circle profile.

Parameters:

  • slon (float) – Longitude of profile start (decimal degrees).

  • slat (float) – Latitude of profile start (decimal degrees).

  • elon (float) – Longitude of profile end (decimal degrees).

  • elat (float) – Latitude of profile end (decimal degrees).

  • d (float) – Maximum distance (km) from profile for a point to be included.

  • save (str, optional) – If provided, write results to this file.

  • verbose (bool, optional) – If True, print progress. Default is False.

Returns:

np_code, np_distance_along_profile, np_distance_to_profile, np_Ve, np_Vn, np_SVe, np_SVn, np_v_parallele, np_v_perpendicular, np_sigma_v_parallele, np_sigma_v_perpendicular, np_lazimuth.

Return type:

tuple

radial(center)

Return a velocity field with radial and tangential components about a center.

Parameters:

center (array_like) – [longitude, latitude] of center in decimal degrees.

Returns:

New velocity field with Ve = radial, Vn = tangential.

Return type:

Velocity_Field

classmethod read(file_name=None, lexclude=[], lonly=[], verbose=False)

Read a GMT psvelo file.

Parameters:

  • file_name (str, optional) – Path to the GMT psvelo file.

  • lexclude (list, optional) – List of site codes to exclude.

  • lonly (list, optional) – If non-empty, only these site codes are included.

  • verbose (bool, optional) – If True, print progress. Default is False.

Returns:

Populated velocity field instance.

Return type:

Velocity_Field

remove_point(code)

Remove a GMT_Point from the velocity field by code.

Parameters:

code (str) – 4-character code of the point to remove.

Returns:

New velocity field without the point (self replaced).

Return type:

Velocity_Field

site(code)

Return a site as a GMT_Point by code.

Parameters:

code (str) – 4-character site code.

Returns:

The site if found, else None.

Return type:

GMT_Point or None

strain(lcode, save=None, method='WLS', verbose=False)

Calculate strain rate from a list of sites.

Parameters:

  • lcode (list) – List of site codes to use.

  • save (str, optional) – File path to save the result. If None, result is only printed.

  • method (str, optional) – ‘WLS’ (weighted least-squares) or ‘L1’. Default is ‘WLS’.

  • verbose (bool, optional) – If True, print progress. Default is False.

Returns:

self.

Return type:

Velocity_Field

subset(lonly=None, lexclude=None)

Return a new Velocity_Field from a subset of sites.

Parameters:

  • lonly (list, optional) – If provided, only these site codes are included.

  • lexclude (list, optional) – If provided, these site codes are excluded (ignored if lonly is set).

Returns:

New velocity field with the subset of sites.

Return type:

Velocity_Field

substract_pole(W=None, type_euler='rot')

Subtract (or add) the prediction of an Euler pole from the velocity field.

Parameters:

  • W (array_like, optional) – Euler pole: either [lon, lat, omega] in deg/Myr or [wx, wy, wz] in rad/yr.

  • type_euler (str, optional) – ‘rot’ for cartesian rotation rate (rad/yr), ‘euler’ for geographic. Default is ‘rot’.

Returns:

New velocity field with pole removed.

Return type:

Velocity_Field

write(out_file=None, lexclude=[], verbose=True, comment='', up=False)

Write the velocity field to a GMT psvelo file.

Parameters:

  • out_file (str, optional) – Output file path. Default is ‘tmp_vel.gmt’ if None.

  • lexclude (list, optional) – List of site codes to exclude from output.

  • verbose (bool, optional) – If True, print progress. Default is True.

  • comment (str, optional) – Comment line written at top of file.

  • up (bool, optional) – If True, write up component instead of east/north. Default is False.