Fitting distribution with fixed parameters in SciPy

问题

Is it possible to fix parameters while fitting distributions in SciPy? For example, this code:

import scipy.stats as st
xx = st.expon.rvs(size=100)
print st.expon.fit(xx, loc=0)

results in non-zero location (loc).

When some parameter is provided to the fit function it is considered as an initial guess. And if it is provided to the constructor (st.expon(loc=0)) the distribution becomes "frozen" and can not be used for fitting.

回答1:

To fix loc, use the argument floc:

print st.expon.fit(xx, floc=0)

E.g.

In [33]: import scipy.stats as st

In [34]: xx = st.expon.rvs(size=100)

In [35]: print st.expon.fit(xx, floc=0)
(0, 0.77853895325584932)

Some related questions:

• Gamma distribution fit error
• Why does the Gamma distribution in SciPy have three parameters?
• Fitting non-normpdf's to histograms in matplotlib

来源：https://stackoverflow.com/questions/21610034/fitting-distribution-with-fixed-parameters-in-scipy