From 4b1bc6815e81b8370ce373b58fb4db1affdec029 Mon Sep 17 00:00:00 2001
From: hedaoyuan <hedaoyuan@github.com>
Date: Tue, 1 Aug 2017 11:45:49 +0800
Subject: [PATCH] Fix comments of slice_projection, and add unit test of
 SliceProjection.

---
 paddle/gserver/tests/test_LayerGrad.cpp       | 20 +++++++++++++++++++
 .../paddle/trainer_config_helpers/layers.py   |  6 +++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/paddle/gserver/tests/test_LayerGrad.cpp b/paddle/gserver/tests/test_LayerGrad.cpp
index 0975c3bc9..00ca4982e 100644
--- a/paddle/gserver/tests/test_LayerGrad.cpp
+++ b/paddle/gserver/tests/test_LayerGrad.cpp
@@ -152,6 +152,26 @@ TEST(Projection, identity) {
   }
 }
 
+TEST(Projection, slice) {
+  ProjectionConfig conf;
+  conf.set_type("slice");
+  conf.set_input_size(100);
+  SliceConfig& slice1 = *conf.add_slices();
+  slice1.set_start(10);
+  slice1.set_end(20);
+  SliceConfig& slice2 = *conf.add_slices();
+  slice2.set_start(50);
+  slice2.set_end(70);
+  conf.set_output_size(30);
+  for (auto useGpu : {false, true}) {
+    testProjectionGrad(conf,
+                       INPUT_DATA,
+                       /* parameterSize */ 0,
+                       /* batchSize */ 100,
+                       useGpu);
+  }
+}
+
 TEST(Projection, scaling) {
   ProjectionConfig conf;
   conf.set_type("scaling");
diff --git a/python/paddle/trainer_config_helpers/layers.py b/python/paddle/trainer_config_helpers/layers.py
index d1c2cecc6..204523352 100755
--- a/python/paddle/trainer_config_helpers/layers.py
+++ b/python/paddle/trainer_config_helpers/layers.py
@@ -539,11 +539,11 @@ def identity_projection(input, offset=None, size=None):
 
 def slice_projection(input, slices):
     """
-    slice_projection can get multiple outputs, and each output is a slice
-    of the input.
+    slice_projection can slice the input value into multiple parts,
+    and then select some of them to merge into a new output.
 
     .. math::
-       output[i] = input.slice(slices[i])
+       output = [input.slices()]
 
     The example usage is:
 
-- 
GitLab