slippy.surface.DiscFreqSurface

class slippy.surface.DiscFreqSurface(frequencies: Sequence[float], amplitudes: Sequence[float] = (1,), phases: Sequence[float] = (0,), rotation: numbers.Number = 0, shift: Optional[tuple] = None, generate: bool = False, grid_spacing: Optional[float] = None, extent: Optional[tuple] = None, shape: Optional[tuple] = None)[source]

Surfaces with discrete frequency components

This surface produces a profile with frequency components which are constant in th y direction, these can be rotated and combined by addition or subtraction to give any combination of frequencies.

Parameters

  • frequencies (Sequence[float]) – The frequencies present in the surface

  • amplitudes (Sequence[float], optional ((1, ))) – The amplitude of each frequency, must be same length as frequencies

  • phases (Sequence[float] = (0,)) – The phases of each of the frequencies, must be the same length as frequencies

  • rotation (Number = 0) – If set the surface is rotated by the set amount, in radians

  • shift (tuple, optional (None)) – If set the origin of the surface is shifted by the set amount in the x and y directions, should be a two element tuple of float. By default, the surface is shifted so that the origin becomes the centre of the surface. To stop this behaviour specify a shift of (0, 0)

  • generate (bool, optional (False)) – If True the surface profile is generated on instantiation, else it can be generated by the discretise method. If True two of the: grid_spacing, extent or shape must also be set

  • grid_spacing (float, optional (None)) – The grid spacing of the surface profile

  • extent (tuple, optional (None)) – The overall dimensions of the surface in the same units as the grid spacing, should be a two element tuple of float

  • shape (tuple = None) – The number of points in each direction of the surface array, should be a two element tuple of integers

See also

ProbFreqSurface, HurstFractalSurface

Notes

Roughness functions are aliased from the functions provided in the surface module

Examples

>>> mySurf=DiscFreqSurface(10, 0.1)
>>> mySurf.extent=[0.5,0.5]
>>> mySurf.discretise(0.001)
__init__(frequencies: Sequence[float], amplitudes: Sequence[float] = (1,), phases: Sequence[float] = (0,), rotation: numbers.Number = 0, shift: Optional[tuple] = None, generate: bool = False, grid_spacing: Optional[float] = None, extent: Optional[tuple] = None, shape: Optional[tuple] = None)[source]

Methods

__init__(frequencies[, amplitudes, phases, ...])

convert_coordinates(y_coord, x_coord)

discretise()

find_summits([mask, four_nearest, ...])

Find summits after low pass filtering

get_acf([profile_in])

Find the auto correlation function of the surface

get_fft([profile_in])

Find the fourier transform of the surface

get_height_of_mat_vr(ratio[, void, mask, ...])

Find the height of a given material or void volume ratio

get_mat_vr(height[, void, mask, ratio])

Find the material or void volume ratio for a given height

get_points_from_extent([extent, ...])

Gets the grid points from the extent and the grid spacing

get_psd()

Find the power spectral density of the surface

get_summit_curvature([summits, mask, ...])

Get summit curvatures

height(x_mesh, y_mesh)

Find the height of the surface at specified points

interpolate(y_points, x_points[, mode, ...])

Easy memoized interpolation on surface objects

low_pass_filter(cut_off_freq[, return_copy])

Low pass FIR filter the surface profile

max_shape()

mesh(depth[, method, parameters])

Returns a Mesh object for the surface

resample([new_grid_spacing, return_profile, ...])

Resample or crop the profile by interpolation

rotate(radians)

roughness(parameter_name[, mask, ...])

Find areal roughness parameters

shift([shift])

Translate the profile of the surface

show([property_to_plot, plot_type, ax, ...])

Plot surface properties

subtract_polynomial(order[, mask])

Flatten the surface by subtracting a polynomial

wear(name, x_pts, y_pts, depth)

Add wear / geometry changes to the surface profile

Attributes

acf

The auto correlation function of the surface profile

dimensions

The number of spatial dimensions that

extent

The overall dimensions of the surface in the same units as grid spacing

fft

The fast fourier transform of the surface

grid_spacing

The distance between grid points in the x and y directions

is_analytic

is_discrete

A bool flag, True if there is a profile present

mask

A mask used to exclude some values from analysis, a single float or an array of bool the same size as profile Either a boolean array of size self.size or a float of the value to be excluded

material

A material object describing the properties of the surface

moving_surface

profile

The height data for the surface profile

psd

The power spectral density of the surface

shape

The shape of the surface profile array, the number of points in each direction

size

The total number of points in the surface

surface_type

A description of the surface type

unworn_profile

wear_volumes