API Documentation

Structure function calculation package. This package calculates structure functions from ocean velocity data.

fluidsf.bin_data(dd, sf, nbins)

Bins the data based on the separation distances and calculates the bin-averaged structure functions.

Parameters:

  • dd (array-like) – The separation distances to be binned.

  • sf (array-like) – The structure functions that will be bin-averaged.

  • nbins (int) – The number of bins to create.

Returns:

A tuple containing the binned separation distances and the bin-averaged structure functions.

Return type:

tuple

fluidsf.calculate_advection_2d(u, v, x, y, dx=None, dy=None, grid_type='uniform', scalar=None)

Calculate the advection for a velocity field or scalar field. The velocity field will return advection components in the x and y directions. The scalar field will return the scalar advection. Defaults to advection for velocity field. If the velocity advection is skipped or a scalar field is not provided, the relevant dictionary key will return None.

Parameters:

  • u (ndarray) – The u-component of velocity.

  • v (ndarray) – The v-component of velocity.

  • x (ndarray) – The x-coordinates of the grid.

  • y (ndarray) – The y-coordinates of the grid.

  • dx (float or ndarray, optional) – The grid spacing in the x-direction. Defaults to None.

  • dy (float or ndarray, optional) – The grid spacing in the y-direction. Defaults to None.

  • grid_type (str, optional) – The type of grid. Defaults to “uniform”.

  • scalar (ndarray, optional) – Array of scalar values. Defaults to None.

Returns:

A tuple of advection components (x and y) if scalar is not provided, otherwise returns an ndarray of scalar advection.

Return type:

tuple or ndarray

fluidsf.calculate_advection_3d(u, v, w, x, y, z, scalar=None)

Calculate the advection for a velocity field or scalar field. The velocity field will return advection components in the x, y, and z directions. The scalar field will return the scalar advection. Defaults to advection for velocity field. If the velocity advection is skipped or a scalar field is not provided, the relevant dictionary key will return None.

Parameters:

  • u (ndarray) – The u-component of velocity.

  • v (ndarray) – The v-component of velocity.

  • w (ndarray) – The w-component of velocity.

  • x (ndarray) – The x-coordinates of the grid.

  • y (ndarray) – The y-coordinates of the grid.

  • z (ndarray) – The z-coordinates of the grid.

  • scalar (ndarray, optional) – Array of scalar values. Defaults to None.

Returns:

A tuple of advection components (x, y, z) if scalar is not provided, otherwise returns an ndarray of scalar advection.

Return type:

tuple or ndarray

fluidsf.calculate_separation_distances(x, y, x_shift, y_shift, grid_type='uniform')

Calculate the separation distances between two points.

Parameters:

  • x (float) – The x-coordinate of the first point.

  • y (float) – The y-coordinate of the first point.

  • x_shift (float) – The x-coordinate of the second point.

  • y_shift (float) – The y-coordinate of the second point.

  • grid_type (str) – The type of grid used for the coordinates. A uniform grid results in a simple distance calculation, but a latlon grid uses geopy’s great_circle function to estimate the distance in meters. Defaults to “uniform”.

Returns:

A tuple containing the x and y separation distances. Either in meters in the case of a latlon grid or code units for a uniform grid

Return type:

tuple

fluidsf.calculate_separation_distances_3d(x, y, z, x_shift, y_shift, z_shift)

Calculate the separation distances between two points.

Parameters:

  • x (float) – The x-coordinate of the first point.

  • y (float) – The y-coordinate of the first point.

  • z (float) – The z-coordinate of the first point.

  • x_shift (float) – The x-coordinate of the second point.

  • y_shift (float) – The y-coordinate of the second point.

  • z_shift (float) – The z-coordinate of the second point.

Returns:

A tuple containing the x, y, and z separation distances. In code units for a uniform grid.

Return type:

tuple

fluidsf.calculate_sf_maps_2d(u, v, x, y, adv_x, adv_y, shift_in_x, shift_in_y, sf_type, scalar=None, adv_scalar=None)

Calculate structure functions, including advective structure functions. Supports velocity-based structure functions and scalar-based structure functions. Can only be used with periodic, evenly-spaced data.

Parameters:

  • u (ndarray) – Array of u velocities.

  • v (ndarray) – Array of v velocities.

  • x (ndarray) – 1D array of x-coordinates.

  • y (ndarray) – 1D array of y-coordinates.

  • adv_x (ndarray) – Array of x-dir advection values.

  • adv_y (ndarray) – Array of y-dir advection values.

  • shift_in_x (int) – Shift amount for x shift.

  • shift_in_y (int) – Shift amount for y shift.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “ASF_V”, “ASF_S”, “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”.

  • scalar (ndarray, optional) – Array of scalar values. Defaults to None.

  • adv_scalar (ndarray, optional) – Array of scalar advection values. Defaults to None.

Returns:

A dictionary containing the advection velocity structure functions and scalar structure functions (if applicable). The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_advection_velocity_xy: The advective velocity structure function for separation vectors in the x-y plane.

SF_advection_scalar_xy: The advective scalar structure function for separation vectors in the x-y plane.

SF_LL_xy: The second-order longitudinal velocity structure function for separation vectors in the x-y plane.

SF_TT_xy: The second-order transverse velocity structure function for separation vectors in the x-y plane.

SF_SS_xy: The second-order scalar structure function for separation vectors in the x-y plane.

SF_LLL_xy: The third-order longitudinal velocity structure function for separation vectors in the x-y plane.

SF_LTT_xy: The third-order longitudinal-transverse-transverse velocity structure function for separation vectors in the x-y plane.

SF_LSS_xy: The third-order longitudinal-scalar-scalar structure function for separation vectors in the x-y plane.

Return type:

dict

fluidsf.calculate_structure_function_1d(u, sep_id, sf_type, v=None, scalar=None, boundary='Periodic')

Calculate structure functions for 1D data. Supports velocity-based structure functions and scalar-based structure functions. Defaults to calculating the third-order longitudinal velocity structure function (‘LLL’) along the data track.

Parameters:

  • u (ndarray) – Array of u velocities.

  • sep_id (ndarray) – Array of separation distances.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to “LLL”. If you include “SS” or “LSS”, you must provide a 1D array for scalar.

  • v (ndarray) – Array of v velocities. Defaults to None.

  • scalar (ndarray, optional) – Array of scalar values. Defaults to None.

  • boundary (str, optional) – Boundary condition for shifting arrays. Defaults to “Periodic”. Set to None if no boundary conditions.

Returns:

A dictionary containing the velocity structure functions and scalar structure functions (if applicable). The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_LL: The second-order longitudinal velocity structure function.

SF_TT: The second-order transverse velocity structure function.

SF_SS: The second-order scalar structure function.

SF_LLL: The third-order longitudinal velocity structure function.

SF_LTT: The third-order longitudinal-transverse-transverse velocity structure function.

SF_LSS: The third-order longitudinal-scalar-scalar structure function.

Return type:

dict

fluidsf.calculate_structure_function_2d(u, v, adv_x, adv_y, shift_x, shift_y, sf_type, scalar=None, adv_scalar=None, boundary='periodic-all')

Calculate structure functions, including advective structure functions. Supports velocity-based structure functions and scalar-based structure functions.

Parameters:

  • u (ndarray) – Array of u velocities.

  • v (ndarray) – Array of v velocities.

  • adv_x (ndarray) – Array of x-dir advection values.

  • adv_y (ndarray) – Array of y-dir advection values.

  • shift_x (int) – Shift amount for x shift.

  • shift_y (int) – Shift amount for y shift.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “ASF_V, “ASF_S”, “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to “ASF_V”.

  • scalar (ndarray, optional) – Array of scalar values. Defaults to None.

  • adv_scalar (ndarray, optional) – Array of scalar advection values. Defaults to None.

  • boundary (str, optional) – Boundary condition for shifting arrays. Accepted strings are “periodic-x”, “periodic-y”, and “periodic-all”. Defaults to “periodic-all”.

Returns:

A dictionary containing the advection velocity structure functions and scalar structure functions (if applicable). The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_advection_velocity_x: The advective velocity structure function in the x direction.

SF_advection_velocity_y: The advective velocity structure function in the y direction.

SF_advection_scalar_x: The advective scalar structure function in the x direction.

SF_advection_scalar_y: The advective scalar structure function in the y direction.

SF_LL_x: The second-order longitudinal velocity structure function in the x direction.

SF_LL_y: The second-order longitudinal velocity structure function in the y direction.

SF_TT_x: The second-order transverse velocity structure function in the x direction.

SF_TT_y: The second-order transverse velocity structure function in the y direction.

SF_SS_x: The second-order scalar structure function in the x direction.

SF_SS_y: The second-order scalar velocity structure function in the y direction.

SF_LLL_x: The third-order longitudinal velocity structure function in the x direction.

SF_LLL_y: The third-order longitudinal velocity structure function in the y direction.

SF_LTT_x: The third-order longitudinal velocity structure function in the x direction.

SF_LTT_y: The third-order longitudinal-transverse-transverse velocity structure function in the y direction.

SF_LSS_x: The third-order longitudinal-scalar-scalar structure function in the x direction.

SF_LSS_y: The third-order longitudinal-scalar-scalar structure function in the y direction.

Return type:

dict

fluidsf.calculate_structure_function_3d(u, v, w, adv_x, adv_y, adv_z, shift_x, shift_y, shift_z, sf_type, scalar=None, adv_scalar=None, boundary='periodic-all')

Calculate structure functions, including advective structure functions. Supports velocity-based structure functions and scalar-based structure functions.

Parameters:

  • u (ndarray) – Array of u velocities.

  • v (ndarray) – Array of v velocities.

  • w (ndarray) – Array of w velocities.

  • adv_x (ndarray) – Array of x-dir advection values.

  • adv_y (ndarray) – Array of y-dir advection values.

  • adv_z (ndarray) – Array of z-dir advection values.

  • shift_x (int) – Shift amount for x shift.

  • shift_y (int) – Shift amount for y shift.

  • shift_z (int) – Shift amount for z shift.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “ASF_V, “ASF_S”, “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to “ASF_V”.

  • scalar (ndarray, optional) – Array of scalar values. Defaults to None.

  • adv_scalar (ndarray, optional) – Array of scalar advection values. Defaults to None.

  • boundary (str, optional) – Boundary condition for shifting arrays. Accepted strings are “periodic-x”, “periodic-y”, “periodic-z” and “periodic-all”. Defaults to “periodic-all”.

Returns:

A dictionary containing the velocity-based advective structure functions and scalar structure functions (if applicable). The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_velocity_x: The advective velocity structure function in the x direction.

SF_velocity_y: The advective velocity structure function in the y direction.

SF_velocity_z: The advective velocity structure function in the z direction.

SF_scalar_x: The advective scalar structure function in the x direction.

SF_scalar_y: The advective scalar structure function in the y direction.

SF_scalar_z: The advective scalar structure function in the z direction.

SF_LL_x: The second-order longitudinal velocity structure function in the x direction.

SF_LL_y: The second-order longitudinal velocity structure function in the y direction.

SF_LL_z: The second-order longitudinal velocity structure function in the z direction.

SF_TT_x: The second-order transverse velocity structure function in the x direction.

SF_TT_y: The second-order transverse velocity structure function in the y direction.

SF_TT_z: The second-order transverse velocity structure function in the z direction.

SF_SS_x: The second-order scalar structure function in the x direction.

SF_SS_y: The second-order scalar structure function in the y direction.

SF_SS_z: The second-order scalar structure function in the z direction.

SF_LLL_x: The third-order longitudinal velocity structure function in the x direction.

SF_LLL_y: The third-order longitudinal velocity structure function in the y direction.

SF_LLL_z: The third-order longitudinal velocity structure function in the z direction.

SF_LTT_x: The third-order longitudinal-transverse-transverse velocity structure function in the x direction.

SF_LTT_y: The third-order longitudinal-transverse-transverse velocity structure function in the y direction.

SF_LTT_z: The third-order longitudinal-transverse-transverse velocity structure function in the z direction.

SF_LSS_x: The third-order longitudinal-scalar-scalar structure function in the x direction.

SF_LSS_y: The third-order longitudinal-scalar-scalar structure function in the y direction.

SF_LSS_z: The third-order longitudinal-scalar-scalar structure function in the z direction.

Return type:

dict

fluidsf.generate_sf_maps_2d(u, v, x, y, sf_type=['ASF_V'], scalar=None, dx=None, dy=None, grid_type='uniform')

Full method for generating 2D maps of structure functions for 2D data, either advective or traditional structure functions. Supports velocity-based and scalar-based structure functions. Defaults to calculating the velocity-based advective structure functions for the x and y directions. Can only be used with evenly-spaced and periodic data.

Parameters:

  • u (ndarray) – 2D array of u velocity components.

  • v (ndarray) – 2D array of v velocity components.

  • x (ndarray) – 1D array of x-coordinates.

  • y (ndarray) – 1D array of y-coordinates.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “ASF_V”, “ASF_S”, “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to [“ASF_V”].

  • scalar (ndarray, optional) – 2D array of scalar values. Defaults to None.

  • dx (float, optional) – Grid spacing in the x-direction. Defaults to None.

  • dy (float, optional) – Grid spacing in the y-direction. Defaults to None.

  • grid_type (str, optional) – Type of grid, can only be “uniform” for these maps.

Returns:

Dictionary containing the requested structure functions and separation distances for the x- and y-directions. The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_advection_velocity_xy: The advective velocity structure function for separation vectors in the x-y plane.

SF_advection_scalar_xy: The advective scalar structure function for separation vectors in the x-y plane.

SF_LL_xy: The second-order longitudinal velocity structure function for separation vectors in the x-y plane.

SF_TT_xy: The second-order transverse velocity structure function for separation vectors in the x-y plane.

SF_SS_xy: The second-order scalar structure function for separation vectors in the x-y plane.

SF_LLL_xy: The third-order longitudinal velocity structure function for separation vectors in the x-y plane.

SF_LTT_xy: The third-order longitudinal-transverse-transverse velocity structure function for separation vectors in the x-y plane.

SF_LSS_xy: The third-order longitudinal-scalar-scalar structure function for separation vectors in the x-y plane.

separation_distances: 2D array of separation distances between points in the x-y plane.

separation_angles: 2D array of angles between points in the x-y plane.

x_separations: 2D array of x-component of separation distance between points in the x-y plane.

y_separations: 2D array of y-component of separation distance between points in the x-y plane.

Return type:

dict

fluidsf.generate_structure_functions_1d(u, x, sf_type=['LLL'], v=None, y=None, scalar=None, dx=None, boundary='Periodic', grid_type='uniform', nbins=None)

Full method for generating traditional structure functions for 1D data. Supports velocity-based and scalar-based structure functions. Defaults to calculating the third-order velocity structure function (‘LLL’) along the data track.

Parameters:

  • u (ndarray) – 1D array of u velocity components.

  • x (ndarray) – 1D array of coordinates. If you have lat-lon data, set x to 1D array of latitudes.

  • sf_type (list) – List of traditional structure function types to calculate. Accepted list entries must be one or more of the following strings: “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to [“LLL”]. If you include “SS” or “LSS”, you must provide a 1D array for scalar.

  • v (ndarray) – 1D array of v velocity components. Defaults to None.

  • y (ndarray, optional) – 1D array of coordinates orthogonal to x. Defaults to None. If you have lat-lon data, set y to 1D array of longitudes.

  • scalar (ndarray, optional) – 1D array of scalar values. Defaults to None.

  • dx (float, optional) – Grid spacing along the data track. Defaults to None.

  • boundary (str, optional) – Boundary condition of the data. Defaults to “Periodic”. Set to None if no boundary conditions.

  • grid_type (str, optional) – Type of grid, either “uniform” or “latlon”. Defaults to “uniform”.

  • nbins (int, optional) – Number of bins for binning the data. Defaults to None, i.e. does not bin data.

Returns:

Dictionary containing the requested structure functions and separation distances along the data track. The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_LL: The second-order longitudinal velocity structure function.

SF_TT: The second-order transverse velocity structure function.

SF_SS: The second-order scalar structure function.

SF_LLL: The third-order longitudinal velocity structure function.

SF_LTT: The third-order longitudinal-transverse-transverse velocity structure function.

SF_LSS: The third-order longitudinal-scalar-scalar structure function.

x-diffs: The separation distances along the data track.

Return type:

dict

fluidsf.generate_structure_functions_2d(u, v, x, y, sf_type=['ASF_V'], scalar=None, dx=None, dy=None, boundary='periodic-all', grid_type='uniform', nbins=None)

Full method for generating structure functions for 2D data, including advective structure functions. Supports velocity-based and scalar-based structure functions. Defaults to calculating the velocity-based advective structure functions for the x and y directions.

Parameters:

  • u (ndarray) – 2D array of u velocity components.

  • v (ndarray) – 2D array of v velocity components.

  • x (ndarray) – 1D array of x-coordinates.

  • y (ndarray) – 1D array of y-coordinates.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “ASF_V, “ASF_S”, “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to [“ASF_V”].

  • scalar (ndarray, optional) – 2D array of scalar values. Defaults to None.

  • dx (float, optional) – Grid spacing in the x-direction. Defaults to None.

  • dy (float, optional) – Grid spacing in the y-direction. Defaults to None.

  • boundary (str, optional) – Boundary condition of the data. Accepted strings are “periodic-x”, “periodic-y”, and “periodic-all”. Defaults to “periodic-all”.

  • grid_type (str, optional) – Type of grid, either “uniform” or “latlon”. Defaults to “uniform”.

  • nbins (int, optional) – Number of bins for binning the data. Defaults to None, i.e. does not bin data.

Returns:

Dictionary containing the requested structure functions and separation distances for the x- and y-direction. The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_advection_velocity_x: The advective velocity structure function in the x direction.

SF_advection_velocity_y: The advective velocity structure function in the y direction.

SF_advection_scalar_x: The advective scalar structure function in the x direction.

SF_advection_scalar_y: The advective scalar structure function in the y direction.

SF_LL_x: The second-order longitudinal velocity structure function in the x direction.

SF_LL_y: The second-order longitudinal velocity structure function in the y direction.

SF_TT_x: The second-order transverse velocity structure function in the x direction.

SF_TT_y: The second-order transverse velocity structure function in the y direction.

SF_SS_x: The second-order scalar structure function in the x direction.

SF_SS_y: The second-order scalar structure function in the y direction.

SF_LLL_x: The third-order longitudinal velocity structure function in the x direction.

SF_LLL_y: The third-order longitudinal velocity structure function in the y direction.

SF_LTT_x: The third-order longitudinal-transverse-transverse velocity structure function in the x direction.

SF_LTT_y: The third-order longitudinal-transverse-transverse velocity structure function in the y direction.

SF_LSS_x: The third-order longitudinal-scalar-scalar structure function in the x direction.

SF_LSS_y: The third-order longitudinal-scalar-scalar structure function in the y direction.

x-diffs: The separation distances in the x direction.

y-diffs: The separation distances in the y direction.

Return type:

dict

fluidsf.generate_structure_functions_3d(u, v, w, x, y, z, sf_type=['ASF_V'], scalar=None, boundary='periodic-all', nbins=None)

Full method for generating structure functions for uniform and even 3D data, including advective structure functions. Supports velocity-based and scalar-based structure functions. Defaults to calculating the velocity-based advective structure functions for the x, y, and z directions.

Parameters:

  • u (ndarray) – 3D array of u velocity components.

  • v (ndarray) – 3D array of v velocity components.

  • w (ndarray) – 3D array of w velocity components.

  • x (ndarray) – 1D array of x-coordinates.

  • y (ndarray) – 1D array of y-coordinates.

  • z (ndarray) – 1D array of z-coordinates.

  • sf_type (list) – List of structure function types to calculate. Accepted list entries must be one or more of the following strings: “ASF_V, “ASF_S”, “LL”, “TT”, “SS”, “LLL”, “LTT”, “LSS”. Defaults to [“ASF_V”].

  • scalar (ndarray, optional) – 3D array of scalar values. Defaults to None.

  • boundary (str, optional) – Boundary condition of the data. Accepted strings are “periodic-x”, “periodic-y”, “periodic-z”, and “periodic-all”. Defaults to “periodic-all”.

  • nbins (int, optional) – Number of bins in the structure function. Defaults to None, i.e. does not bin the data.

Returns:

Dictionary containing the requested structure functions and separation distances for the x, y, and z directions. The returned dictionary may contain the following keys, with some keys removed if the structure function is not calculated:

SF_advection_velocity_x: The advective velocity structure function in the x direction.

SF_advection_velocity_y: The advective velocity structure function in the y direction.

SF_advection_velocity_z: The advective velocity structure function in the z direction.

SF_advection_scalar_x: The advective scalar structure function in the x direction.

SF_advection_scalar_y: The advective scalar structure function in the y direction.

SF_advection_scalar_z: The advective scalar structure function in the z direction.

SF_LL_x: The second-order longitudinal velocity structure function in the x direction.

SF_LL_y: The second-order longitudinal velocity structure function in the y direction.

SF_LL_z: The second-order longitudinal velocity structure function in the z direction.

SF_TT_x: The second-order transverse velocity structure function in the x direction.

SF_TT_y: The second-order transverse velocity structure function in the y direction.

SF_TT_z: The second-order transverse velocity structure function in the z direction.

SF_SS_x: The second-order scalar structure function in the x direction.

SF_SS_y: The second-order scalar structure function in the y direction.

SF_SS_z: The second-order scalar structure function in the z direction.

SF_LLL_x: The third-order longitudinal velocity structure function in the x direction.

SF_LLL_y: The third-order longitudinal velocity structure function in the y direction.

SF_LLL_z: The third-order longitudinal velocity structure function in the z direction.

SF_LTT_x: The third-order longitudinal-transverse-transverse velocity structure function in the x direction.

SF_LTT_y: The third-order longitudinal-transverse-transverse velocity structure function in the y direction.

SF_LTT_z: The third-order longitudinal-transverse-transverse velocity structure function in the z direction.

SF_LSS_x: The third-order longitudinal-scalar-scalar velocity structure function in the x direction.

SF_LSS_y: The third-order longitudinal-scalar-scalar velocity structure function in the y direction.

SF_LSS_z: The third-order longitudinal-scalar-scalar velocity structure function in the z direction.

x-diffs: The separation distances in the x direction.

y-diffs: The separation distances in the y direction.

z-diffs: The separation distances in the z direction.

Return type:

dict

fluidsf.shift_array_1d(input_array, shift_by=1, boundary='Periodic')

Shifts 1D array by an integer amount and returns the shifted array. Either wraps the array or shifts and pads with NaNs.

Parameters:

  • input_array (array_like) – 1-dimensional array to be shifted.

  • shift_by (int, optional) – Shift amount for array. For periodic data should be less than len(input_array)/2 and less than len(input_array) for other boundary conditions. Defaults to 1.

  • boundary (str, optional) – Boundary condition for input array. Periodic boundary conditions will wrap the array, otherwise the array will be padded with NaNs. Defaults to “Periodic”.

Returns:

1D array shifted by requested integer amount

Return type:

shifted_array

fluidsf.shift_array_2d(input_array, shift_x=1, shift_y=1, boundary='periodic-all')

Shifts 2D array in x and y by the specified integer amounts and returns the shifted arrays. Either wraps the array or shifts and pads with NaNs.

Parameters:

  • input_array (array_like) – 2-dimensional array to be shifted.

  • shift_x (int, optional) – Shift amount in x direction. For periodic data should be less than half the row length and less than the row length for other boundary conditions. Defaults to 1.

  • shift_y (int, optional) – Shift amount in y direction. For periodic data should be less than half the column length and less than the column length for other boundary conditions. Defaults to 1.

  • boundary (str, optional) – Boundary condition for input array. Periodic boundary conditions will wrap the array, otherwise the array will be padded with NaNs. Accepted strings are “periodic-x”, “periodic-y”, and “periodic-all”. Defaults to “periodic-all”.

Returns:

  • shifted_x_array – 2D array shifted in x by the specified integer amount

  • shifted_y_array – 2D array shifted in y by the specified integer amount

fluidsf.shift_array_3d(input_array, shift_x=1, shift_y=1, shift_z=1, boundary=None)

Shifts 3D array in x/y/z by the specified integer amounts and returns the shifted arrays. Either wraps the array or shifts and pads with NaNs.

Parameters:

  • input_array (array_like) – 3-dimensional array to be shifted.

  • shift_x (int, optional) – Shift amount in x direction. For periodic data should be less than half the row length and less than the row length for other boundary conditions. Defaults to 1.

  • shift_y (int, optional) – Shift amount in y direction. For periodic data should be less than half the column length and less than the column length for other boundary conditions. Defaults to 1.

  • shift_z (int, optional) – Shift amount in z direction. For periodic data should be less than half the depth length and less than the depth length for other boundary conditions. Defaults to 1.

  • boundary (list, optional) – List of boundary conditions for input array. Periodic boundary conditions will wrap the array, otherwise the array will be padded with NaNs. Accepted strings are “periodic-x”, “periodic-y”, “periodic-z”, and “periodic-all”. Defaults to “periodic-all”.

Returns:

  • shifted_x_array – 3D array shifted in x by the specified integer amount

  • shiftedy_array – 3D array shifted in y by the specified integer amount

  • shifted_z_array – 3D array shifted in z by the specified integer amount

fluidsf.shift_array_xy(input_array, x_shift=0, y_shift=0)

Wrap 2D array in x and y by the specified integer amounts and returns the shifted arrays. Only works with 2D, doubly-periodic data on an even grid.

Parameters:

  • input_array (array_like) – 2-dimensional array to be shifted.

  • shift_x (int, optional) – Shift amount for x shift.

  • shift_y (int, optional) – Shift amount for y shift.

Returns:

2D array shifted in the x-y directions by the specified integer amount

Return type:

shifted_xy_array