first draft of Binomial.icdf issue pymc-devs#6612

niknow · niknow · commit 0f2cf84306e1 · 2024-06-15T17:02:20.000+01:00
diff --git a/pymc/distributions/discrete.py b/pymc/distributions/discrete.py
@@ -173,6 +173,10 @@ def logcdf(value, n, p):
             msg="n >= 0, 0 <= p <= 1",
         )
 
+    def icdf(value, n, p):
+        cdf_vals = Binomial.logcdf(pt.arange(0, n), n, p)
+        return pt.argmax(cdf_vals > pt.log(value))
+
 
 class BetaBinomial(Discrete):
     R"""

Original file line number	Diff line number	Diff line change
`@@ -173,6 +173,10 @@ def logcdf(value, n, p):`
`173`	`173`	`msg="n >= 0, 0 <= p <= 1",`
`174`	`174`	`)`
`175`	`175`
	`176`	`+ def icdf(value, n, p):`
	`177`	`+ cdf_vals = Binomial.logcdf(pt.arange(0, n), n, p)`
	`178`	`+ return pt.argmax(cdf_vals > pt.log(value))`
	`179`	`+`
`176`	`180`
`177`	`181`	`class BetaBinomial(Discrete):`
`178`	`182`	`R"""`