I'm doing survival calculations in Scipy and can't get the correct values.
My code:
x, a, c = 1000, 1.5, 5000
vals = exponweib.cdf(x,a,c,loc=0,scale=1)
Val should equal 0.085559356392783004, but I'm getting 0 instead.
If I define my own function I get the right answer: def weibCumDist(x,a,c): return 1-np.exp(-(x/c)**a)
I could just use my own function, but I'm curious as to what I'm doing wrong. Any suggestions?
Thanks.
You haven't correctly mapped your parameters to those of scipy. To implement the equivalent of your weibCumDist
:
In [22]: x = 1000
In [23]: a = 1.5
In [24]: c = 5000
In [25]: exponweib.cdf(x, 1, a, loc=0, scale=c)
Out[25]: 0.08555935639278299
Note that exponweib
is the exponentiated Weibull distribution.
You probably want to use scipy.stats.weibull_min
. This is the implementation of the distribution that is often referred to as "the" Weibull distribution:
In [49]: from scipy.stats import weibull_min
In [50]: weibull_min.cdf(x, a, loc=0, scale=c)
Out[50]: 0.08555935639278299
来源:https://stackoverflow.com/questions/27432222/scipy-weibull-cdf-calculation