shakelib.correlation.ccf_base

class shakelib.correlation.ccf_base.CrossCorrelationBase(periods)

Bases: abc.ABC

The abstract base class of cross-correlation functions.

The derived class should take an array of periods as its single argument. These are the periods to which the index arrays of the getCorrelation() method will refer.

abstract getCorrelation(ix1, ix2, h)

Compute the correlation between two periods and a separation distance of h km. ix1 and ix2 give the indices into the array of periods that is provided to the class constructor. The code is implemented in this somewhat awkward way for performance reasons. See the loth_baker_2013 module for an example.

The index arrays (ix1 and ix2) and h array must have the same dimensions. The indices may be equal, and there is no restriction on which one is larger. The indices refer to periods in the ‘period’ argument to the class constructor.

Parameters:

• ix1 (ndarray) – The indices of the first period of interest.

• ix2 (ndarrays) – The indices of the second period of interest.

• h (ndarray) – The separation distance between two sites (units of km). The result is placed in h, so h must be copied if it is to be preserved.

Returns:

The predicted correlation coefficient. The output array will have the same shape as the inputs.

Return type:

h (ndarray)