refine check_parameter, use proper type mapping (#75)

src/LIBSVM.jl

@@ -262,11 +262,9 @@ function set_num_threads(nt::Integer)
     ccall((:svm_set_num_threads, libsvm), Cvoid, (Cint,), nt)
 end
 
-function check_parameter(problem::Vector{SVMProblem}, param::Vector{SVMParameter})
-    @assert length(problem) == 1
-    @assert length(param) == 1
+function check_parameter(problem::SVMProblem, param::SVMParameter)
     err = ccall((:svm_check_parameter, libsvm), Cstring,
-                (Ptr{SVMProblem}, Ptr{SVMParameter}),
+                (Ref{SVMProblem}, Ref{SVMParameter}),
                 problem, param)
     if err != C_NULL
         throw(ArgumentError("Incorrect parameter: $(unsafe_string(err))"))
@@ -359,16 +357,15 @@ function svmtrain(
         idx, reverse_labels, weights, weight_labels = indices_and_weights(y, X, weights)
     end
 
-    param = Array{SVMParameter}(undef, 1)
-    param[1] = SVMParameter(_svmtype, _kernel, Int32(degree), Float64(gamma),
+    param = SVMParameter(
+        _svmtype, _kernel, Int32(degree), Float64(gamma),
         coef0, cachesize, tolerance, cost, Int32(length(weights)),
         pointer(weight_labels), pointer(weights), nu, epsilon, Int32(shrinking),
         Int32(probability))
 
     # Construct SVMProblem
     (nodes, nodeptrs) = instances2nodes(X)
-    problem = SVMProblem[SVMProblem(Int32(size(X, 2)), pointer(idx),
-        pointer(nodeptrs))]
+    problem = SVMProblem(Int32(size(X, 2)), pointer(idx), pointer(nodeptrs))
 
     # Validate the given parameters
     check_parameter(problem, param)
@@ -382,10 +379,10 @@ function svmtrain(
               (Ptr{Cvoid},), @cfunction(svmnoprint, Cvoid, (Ptr{UInt8},)))
     end
 
-    mod = ccall((:svm_train, libsvm), Ptr{SVMModel}, (Ptr{SVMProblem},
-        Ptr{SVMParameter}), problem, param)
-    svm = SVM(unsafe_load(mod), y, X, wts, reverse_labels,
-        svmtype, kernel)
+    mod = ccall((:svm_train, libsvm), Ptr{SVMModel},
+                (Ref{SVMProblem}, Ref{SVMParameter}),
+                problem, param)
+    svm = SVM(unsafe_load(mod), y, X, wts, reverse_labels, svmtype, kernel)
 
     ccall((:svm_free_model_content, libsvm), Cvoid, (Ptr{Cvoid},), mod)
     return svm