# biotite.structure.density¶

biotite.structure.density(atoms, selection=None, delta=1.0, bins=None, density=False, weights=None)[source]

Compute the density of the selected atoms.

This creates a 3d histogram over the coordinates of selected atoms. By default, the grid for the histogram is built based on the coordinates of the given atoms with an even gridspacing of delta in all three dimensions. Alternatively, a custom grid can be used.

Parameters
atomsAtomArray or AtomArrayStack or ndarray, shape=(n,3) or shape=(m,n,3)

The density is calculated based on these atoms. Alternatively, the coordinates can be directly provided as ndarray.

selectionndarray, dtype=bool, shape=(n,), optional

Boolean mask for atoms to calculate the density only on a set of atoms.

deltafloat, optional

Distance between grid points for density calculation (in Å).

binsint or sequence of scalars or str, optional

Bins for the RDF.

• If bins is an int, it defines the number of bins.

• If bins is a sequence, it defines the bin edges, ignoring the actual coordinates of the atoms selection.

• If bins is a string, it defines the function used to calculate the bins.

See `numpy.histogramdd()` for further details.

densityboolean, optional

If False, the number of samples in each bin is returned. Otherwise, returns the probability density function of each bin. See `numpy.histogramdd()` for further details.

weights: ndarray, shape=(n,) or shape=(m,n), optional

An array of values to weight the contribution of n atoms in m models. If the shape is (n,), the weights will be interpreted as per atom. A shape of (m,n) allows to additionally weight atoms on a per model basis.

Returns
Hndarray, dtype=float

The threedimensional histogram of the selected atoms. The histogram takes the atoms in all models into account. The length of the histogram depends on atoms coordinates and delta, or the supplied bins input parameter.

edgeslist of ndarray, dtype=float

A list containing the 3 arrays describing the bin edges.