Add Constructor to FisherExactTest

src/fisher.jl

@@ -26,11 +26,17 @@ export FisherExactTest
 
 """
     FisherExactTest(a::Integer, b::Integer, c::Integer, d::Integer)
+    FisherExactTest(x[, y])
 
 Perform Fisher's exact test of the null hypothesis that the success probabilities ``a/c``
 and ``b/d`` are equal, that is the odds ratio ``(a/c) / (b/d)`` is one, against the
 alternative hypothesis that they are not equal.
 
+If `x` is a matrix with at least two rows and columns, it is taken as a two-dimensional
+contingency table. Otherwise, `x` and `y` must be vectors of the same length. The contingency
+table is calculated using `counts` function from the `StatsBase` package.
+Note that the entries of `x` (and `y` if provided) must be non-negative integers.
+
 See [`pvalue(::FisherExactTest)`](@ref) and [`confint(::FisherExactTest)`](@ref) for details
 about the computation of the default p-value and confidence interval, respectively.
 
@@ -73,6 +79,15 @@ struct FisherExactTest <: HypothesisTest
     end
 end
 
+function FisherExactTest(x::AbstractMatrix{T}) where T<:Integer
+    FisherExactTest(x[1,1], x[1,2], x[2,1], x[2,2])
+end
+
+function FisherExactTest(x::AbstractVector{T}, y::AbstractVector{T}) where T<:Integer
+    d = counts(x, y)
+    FisherExactTest(d[1,1], d[1,2], d[2,1], d[2,2])
+end
+
 testname(::FisherExactTest) = "Fisher's exact test"
 population_param_of_interest(x::FisherExactTest) = ("Odds ratio", 1.0, x.ω) # parameter of interest: name, value under h0, point estimate
 default_tail(test::FisherExactTest) = :both

test/fisher.jl

@@ -1,4 +1,5 @@
 using HypothesisTests, Test
+using StatsBase
 using HypothesisTests: default_tail
 
 @testset "Fisher" begin
@@ -107,4 +108,14 @@ show(IOBuffer(), t)
 t = HypothesisTests.FisherExactTest(1, 1, 1, 1)
 @test HypothesisTests.pvalue(t, tail=:both) <= 1
 show(IOBuffer(), t)
+
+# constructor test for matrix and vectors
+x=[1,1,1,0,0,0,0,0,1,1]
+y=[1,1,0,0,1,0,1,1,1,1]
+
+d = counts(x,y)
+
+FisherExactTest(d)
+FisherExactTest(x,y)
+
 end