openpiv_cxx.validate.local_median

openpiv_cxx.validate.local_median(u, v, mask=None, threshold_u=3.0, threshold_v=3.0, threshold=None, size=2, kernel_min_size=1, convention='openpiv')

Eliminate spurious vectors with a local median threshold.

This validation method tests for the spatial consistency of the data. Vectors are classified as outliers and replaced with Nan (Not a Number) if the absolute difference with the local median is greater than a user specified threshold. The median is computed for both velocity components.

Parameters:

  • u (ndarray) – A two dimensional array containing the u velocity component.

  • v (ndarray) – A two dimensional array containing the v velocity component.

  • mask (ndarray, optional) – A two dimensional array containing the flags for invalid vectors.

  • threshold_u (float) – Threshold for u component.

  • threshold_v (float) – Threshold for v component.

  • threshold (float, optional) – Set thresholds for both u and v components.

  • size (int) – The radius of the median kernel.

  • kernel_min_size (int) – The minimum amount of non-NaN values in a kernel. If less, the kernel is marked as invalid due to not enough valid points.

  • convention (str) – Which flag convention to use.

Returns:

  • u (ndarray, optional) – A two dimensional array containing the u velocity component, where spurious vectors have been replaced by NaN if convention is set to ‘openpiv’.

  • v (ndarray, optional) – A two dimensional array containing the v velocity component, where spurious vectors have been replaced by NaN if convention is set to ‘openpiv’.

  • mask (ndarray) – A boolean or integer array where elemtents that = 0 are valid and 1 = invalid.