slippy.surface.Surface

class slippy.surface.Surface(profile: Optional[numpy.ndarray] = None, grid_spacing: Optional[float] = None, shape: Optional[tuple] = None, extent: Optional[tuple] = None, file_name: Optional[str] = None, mat_profile_name: Optional[str] = None, mat_grid_spacing_name: Optional[str] = None, csv_delimiter: Optional[str] = None, csv_dialect: Union[csv.Dialect, str] = 'sniff', csv_sniffer_n_bytes: int = 2048)[source]

Object for reading, manipulating and plotting surfaces

The Surface class contains methods for setting properties, examining measures of roughness and descriptions of surfaces, plotting, fixing and editing surfaces.

Parameters

  • profile (np.ndarray, optional (None)) – The height profile of the surface, the units should be the same as used for the grid spacing parameter

  • grid_spacing (float, optional (None)) – The distance between the grid points in the surface profile

  • shape (tuple, optional (None)) – The number of grid points in the surface in each direction, should not be set if a profile is given

  • extent (tuple, optional (None)) – The total extent of the surface in the same units as the grid spacing, either this or the grid spacing can be set if a profile is given (either as the profile argument or from a file)

  • file_name (str, optional (None)) – The full path including the file extension to a supported file type, supported types are .txt, .csv, .al3d, .mat

  • csv_delimiter (str, optional (None)) – The delimiter used in the .csv or .txt file, only used if the file name is given and the file is a .txt or .csv file

  • csv_dialect ({csv.Dialect, str), optional ('sniff')) – The dialect used to read the csv file, only used if a file is supplied and the file is a csv file, defaults to ‘sniff’ meaning that the csv. sniffer will be used.

  • csv_sniffer_n_bytes (int, optional (2048)) – The number of bytes used by the csv sniffer, only used if ‘sniff’ is given as the dialect and a csv file is given as the file name

  • mat_profile_name (str, optional ('profile')) – The name of the profile variable in the .mat file, only used if the file_name is given and the file is a .mat file

  • mat_grid_spacing_name (str, optional (None)) – The name of the grid_spacing variable in the .mat file, only used if the file_name is given and the file is a .mat file. If unset the grid_spacing property is not read from the file.

See also

ACF, roughness

Notes

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

Examples

Making a surface from a numpy array:

>>> import slippy.surface as s
>>> import numpy as np
>>> profile = np.random.rand(10,10)
>>> my_surface = s.Surface(profile = profile, grid_spacing = 1)

Making a surface from a csv file:

>>> my_surface = s.Surface(file_name='surface.csv', grid_spacing = 1)

Note that variations on csv files can be handled by passing a CSV dialect object from the csv package, this can also be automatically detected by passing ‘sniff’ as the dialect.

Making a surface from an alicona file:

>>> path = r'path\to\alicona\file'
>>> my_surface = s.Surface(file_name=path+r'\dem.al3d')

This will extract the surface profile and grid spacing from the .al3d file. More parameters can be extracted by using the alicona_read function.

Making a surface from a matlab file:

>>> my_surface = s.Surface(file_name='saved profiles.mat', grid_spacing = 1)

If the profile parameter in the matlab file is not called ‘profile’ this can be set:

>>> my_surface = s.Surface(file_name='saved profiles.mat', mat_profile_name='profile_b', grid_spacing = 1)
__init__(profile: Optional[numpy.ndarray] = None, grid_spacing: Optional[float] = None, shape: Optional[tuple] = None, extent: Optional[tuple] = None, file_name: Optional[str] = None, mat_profile_name: Optional[str] = None, mat_grid_spacing_name: Optional[str] = None, csv_delimiter: Optional[str] = None, csv_dialect: Union[csv.Dialect, str] = 'sniff', csv_sniffer_n_bytes: int = 2048)[source]

Methods

__init__([profile, grid_spacing, shape, ...])

convert_coordinates(y_coord, x_coord)

fill_holes([hole_value, mk_copy, ...])

Replaces specified values with filler

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

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

read_al3d(file_name[, return_data])

Reads an alicona al3d file and sets the profile and grid_spacing property of the surface

read_csv(file_name[, delimiter, ...])

Read a profile from a csv or txt file, header lines are automatically skipped

read_mat(path[, profile_name, grid_spacing_name])

Reads .mat files as surfaces

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

Resample or crop the profile by interpolation

rotate(radians)

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

Find areal roughness parameters

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