def plotting_pos(nobs, a):
 return ((np.arange(1.0, (nobs + 1)) - a) / ((nobs - (2 * a)) + 1))

def plotting_pos ( nobs , a ) : return ( ( np . arange ( 1.0 , ( nobs + 1 ) ) - a ) / ( ( nobs - ( 2 * a ) ) + 1 ) )
generates sequence of plotting positions parameters nobs : int number of probability points to plot a : float offset for the plotting position of an expected order statistic .