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plotting_positions

class reliability.Probability_plotting.plotting_positions(failures=None, right_censored=None, a=None, sort=False)

Calculates the plotting positions for plotting on probability paper.

Parameters:

• failures (array, list) – The failure data. Must have at least 1 element.

• right_censored (array, list, optional) – The right censored failure data. Optional input. Default = None.

• a (float, int, optional) – The heuristic constant for plotting positions of the form (k-a)/(n+1-2a) where k is the rank and n is the number of points. Optional input. Default is a = 0.3 which is the median rank method (same as the default in Minitab and Reliasoft). Must be in the range 0 to 1. For more heuristics, see: https://en.wikipedia.org/wiki/Q%E2%80%93Q_plot#Heuristics

• sort (bool, optional) – Whether the output should be sorted. Default is False.

Returns:

(array(x),array(y)) (tuple) – a tuple of two arrays. The arrays provide the x and y plotting positions. The x array will match the failures parameter while the y array will be the empirical estimate of the CDF at each of the failures.

Notes

This function is primarily used by the probability plotting functions.