Added more overloads of randomly_subsample() that can operate on random_subset_selector

objects.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403648

dlib/statistics/random_subset_selector.h

@@ -267,6 +267,43 @@ namespace dlib
         return subset;
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        >
+    random_subset_selector<T> randomly_subsample (
+        const random_subset_selector<T>& samples,
+        unsigned long num
+    )
+    {
+        random_subset_selector<T> subset;
+        subset.set_max_size(num);
+        for (unsigned long i = 0; i < samples.size(); ++i)
+            subset.add(samples[i]);
+        return subset;
+    }
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T,
+        typename U
+        >
+    random_subset_selector<T> randomly_subsample (
+        const random_subset_selector<T>& samples,
+        unsigned long num,
+        const U& random_seed
+    )
+    {
+        random_subset_selector<T> subset;
+        subset.set_seed(cast_to_string(random_seed));
+        subset.set_max_size(num);
+        for (unsigned long i = 0; i < samples.size(); ++i)
+            subset.add(samples[i]);
+        return subset;
+    }
+
 // ----------------------------------------------------------------------------------------
 
 }

dlib/statistics/random_subset_selector_abstract.h

@@ -283,6 +283,49 @@ namespace dlib
               generator used by this function.
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        >
+    random_subset_selector<T> randomly_subsample (
+        const random_subset_selector<T>& samples,
+        unsigned long num
+    );
+    /*!
+        ensures
+            - returns a random subset R such that:
+                - R contains a random subset of the given samples
+                - R.size() == min(num, samples.size())
+                - R.max_size() == num
+            - The random number generator used by this function will always be
+              initialized in the same way.  I.e. this function will always pick
+              the same random subsample if called multiple times.
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T,
+        typename U
+        >
+    random_subset_selector<T> randomly_subsample (
+        const random_subset_selector<T>& samples,
+        unsigned long num,
+        const U& random_seed
+    );
+    /*!
+        requires
+            - random_seed must be convertible to a string by dlib::cast_to_string()
+        ensures
+            - returns a random subset R such that:
+                - R contains a random subset of the given samples
+                - R.size() == min(num, samples.size())
+                - R.max_size() == num
+            - The given random_seed will be used to initialize the random number
+              generator used by this function.
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
 }