added src/expr-xtra.h

trevorcohn · Apr 15, 2016 · 7524f08 · 7524f08
1 parent 0882db1
commit 7524f08
Showing 1 changed file with 67 additions and 0 deletions.
diff --git a/src/expr-xtra.h b/src/expr-xtra.h
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+#pragma once
+
+#include "cnn/nodes.h"
+#include "cnn/cnn.h"
+#include "cnn/training.h"
+#include "cnn/timing.h"
+#include "cnn/rnn.h"
+#include "cnn/gru.h"
+#include "cnn/lstm.h"
+#include "cnn/dict.h"
+#include "cnn/expr.h"
+
+using namespace cnn;
+
+// Chris -- this should be a library function
+Expression arange(ComputationGraph &cg, unsigned begin, unsigned end, bool log_transform, std::vector<float> *aux_mem) 
+{
+    aux_mem->clear();
+    for (unsigned i = begin; i < end; ++i) 
+        aux_mem->push_back((log_transform) ? log(1.0 + i) : i);
+    return Expression(&cg, cg.add_input(Dim({end-begin}), aux_mem));
+}
+
+// Chris -- this should be a library function
+Expression repeat(ComputationGraph &cg, unsigned num, float value, std::vector<float> *aux_mem) 
+{
+    aux_mem->clear();
+    aux_mem->resize(num, value);
+    return Expression(&cg, cg.add_input(Dim({num}), aux_mem));
+}
+
+// Chris -- this should be a library function
+Expression dither(ComputationGraph &cg, const Expression &expr, float pad_value, std::vector<float> *aux_mem)
+{
+    const auto& shape = cg.nodes[expr.i]->dim;
+    aux_mem->clear();
+    aux_mem->resize(shape.cols(), pad_value);
+    Expression padding(&cg, cg.add_input(Dim({shape.cols()}), aux_mem));
+    Expression padded = concatenate(std::vector<Expression>({padding, expr, padding}));
+    Expression left_shift = pickrange(padded, 2, shape.rows()+2);
+    Expression right_shift = pickrange(padded, 0, shape.rows());
+    return concatenate_cols(std::vector<Expression>({left_shift, expr, right_shift}));
+}
+
+// these expressions can surely be implemented much more efficiently than this
+Expression abs(const Expression &expr) 
+{
+    return rectify(expr) + rectify(-expr); 
+}
+
+// binary boolean functions, is it better to use a sigmoid?
+Expression eq(const Expression &expr, float value, float epsilon=0.1) 
+{
+    return min(rectify(expr - (value - epsilon)), rectify(-expr + (value + epsilon))) / epsilon; 
+}
+
+Expression geq(const Expression &expr, float value, Expression &one, float epsilon=0.01) 
+{
+    return min(one, rectify(expr - (value - epsilon)) / epsilon);
+        //rectify(1 - rectify(expr - (value - epsilon)));
+}
+
+Expression leq(const Expression &expr, float value, Expression &one, float epsilon=0.01) 
+{
+    return min(one, rectify((value + epsilon) - expr) / epsilon);
+    //return rectify(1 - rectify((value + epsilon) - expr));
+}