P-value from Chi sq test statistic in Python

Question

I have computed a test statistic that is distributed as a chi square with 1 degree of freedom, and want to find out what P-value this corresponds to using python.

I

Answer 1

For ultra-high precision, when scipy's chi2.sf() isn't enough, bring out the big guns:

>>> import numpy as np
>>> from rpy2.robjects import r
>>> np.exp(np.longdouble(r.pchisq(19000, 2, lower_tail=False, log_p=True)[0]))
1.5937563168532229629e-4126