`RectGrid`#

class acoular.grids.RectGrid

Bases: Grid

Provides a 2D Cartesian grid for beamforming results.

This grid is composed of square or nearly square cells and lies on a plane perpendicular to the z-axis. It is defined by the lower and upper x- and y-limits and a constant z-coordinate.

x_min: The lower x-limit that defines the grid. Default is -1.

x_max: The upper x-limit that defines the grid. Default is 1.

y_min: The lower y-limit that defines the grid. Default is -1.

y_max: The upper y-limit that defines the grid. Default is 1.

z: The constant z-coordinate of the grid plane. Default is 1.0.

increment: The side length of each cell. Default is 0.1.

nxsteps: Number of grid points along x-axis. (read-only)

nysteps: Number of grid points along y-axis. (read-only)

extent: The grid’s extension in matplotlib.pyplot.imshow compatible form. (read-only)

digest: A unique identifier for the grid, based on its properties. (read-only)

index(x, y)

Find the indices of a grid point near a given coordinate.

Parameters:

xfloat: The x coordinate of interest.
yfloat: The y coordinate of interest.

Returns:

tuple of ints: Indices corresponding to the nearest grid point.

Raises:

ValueError: If the coordinates are outside the grid boundaries.

indices(*r)

Find the indices of a subdomain in the grid.

Supports rectangular, circular, and polygonal subdomains.

Parameters:

rtuple of floats

Defines the subdomain shape and dimensions:

If 3 values are provided: center (x1, y1) and radius r2 define a circle.
If 4 values are provided: corners (x1, y1) and (x2, y2) define a rectangle.
If more than 4 values are provided: vertices (xn, yn) define a polygon.

Returns:

tuple: A 2-tuple of indices or slices corresponding to the subdomain.

export_gpos(filename)

Export the grid positions to an XML file.

This method generates an XML file containing the positions of all grid points. Each point is represented by a <pos> element with Name, x, y, and z attributes. The generated XML is formatted to match the structure required for importing into the ImportGrid class.

Parameters:

filenamestr: The path to the file to which the grid positions will be written. The file extension must be .xml.

Raises:

OSError: If the file cannot be written due to permissions issues or invalid file paths.

Notes

The file will be saved in UTF-8 encoding.
The Name attribute for each point is set as "Point {i+1}", where i is the index of the grid point.
If subgrids are defined, they will be included as the subgrid attribute.

Examples

Export a grid with 100 points to an XML file:

>>> import acoular as ac
>>> import numpy as np
>>> grid = ac.ImportGrid()
>>> # Create some grid points
>>> points = np.arange(9).reshape(3, 3)
>>> grid.pos = points
>>> grid.export_gpos('grid_points.xml')

The generated grid_points.xml file will look like this:

<?xml version="1.1" encoding="utf-8"?><Grid name="grid_points">
  <pos Name="Point 1" x="0" y="1" z="2"/>
  <pos Name="Point 2" x="3" y="4" z="5"/>
  <pos Name="Point 3" x="6" y="7" z="8"/>
</Grid>

subdomain(sector)

Return the indices for a subdomain in the grid.

Allows arbitrary subdomains of type Sector.

Parameters:

sectorSector object: Sector describing the subdomain.

Returns:

tuple: A 2-tuple of arrays of integers or numpy.s_ objects that can be used to mask or select the specified subdomain from a grid-shaped array.

Notes

The numpy.where() method is used to determine the the indices.

size: The total number of grid points. This property is automatically calculated based on other defining attributes of the grid. (read-only)

shape: The shape of the grid, represented as a tuple. Primarily useful for Cartesian grids. (read-only)

pos: The grid positions represented as a (3, size) array of floats. (read-only) All positions’ coordinates are in meters by default (see here).

RectGrid#

`RectGrid`#