feat: add min pooling

automated_test.py

@@ -360,56 +360,56 @@ def test_downsample_segmentation_4x_x():
   result, = downsamplefn(result, (1,2,2))
   assert result.shape == (1024, 16, 128, 1)
 
-def test_downsample_max_pooling():
-  for dtype in (np.int8, np.float32):
-    cases = [
-      np.array([ [ -1, 0 ], [ 0, 0 ] ], dtype=dtype), 
-      np.array([ [ 0, 0 ], [ 0, 0 ] ], dtype=dtype), 
-      np.array([ [ 0, 1 ], [ 0, 0 ] ], dtype=dtype),
-      np.array([ [ 0, 1 ], [ 1, 0 ] ], dtype=dtype),
-      np.array([ [ 0, 1 ], [ 0, 2 ] ], dtype=dtype)
-    ]
-
-    for i in range(len(cases)):
-      case = cases[i]
-      result, = tinybrain.downsample.downsample_with_max_pooling(case, (1, 1))
-      assert np.all(result == cases[i])
+@pytest.mark.parametrize("dtype", [np.int8, np.float32])
+def test_downsample_max_pooling(dtype):
+  cases = [
+    np.array([ [ -1, 0 ], [ 0, 0 ] ], dtype=dtype), 
+    np.array([ [ 0, 0 ], [ 0, 0 ] ], dtype=dtype), 
+    np.array([ [ 0, 1 ], [ 0, 0 ] ], dtype=dtype),
+    np.array([ [ 0, 1 ], [ 1, 0 ] ], dtype=dtype),
+    np.array([ [ 0, 1 ], [ 0, 2 ] ], dtype=dtype)
+  ]
 
-    answers = [ 0, 0, 1, 1, 2 ]
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_max_pooling(case, (1, 1))
+    assert np.all(result == cases[i])
 
-    for i in range(len(cases)):
-      case = cases[i]
-      result, = tinybrain.downsample.downsample_with_max_pooling(case, (2, 2))
-      assert result == answers[i]
+  answers = [ 0, 0, 1, 1, 2 ]
 
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_max_pooling(case, (2, 2))
+    assert result == answers[i]
 
-    cast = lambda arr: np.array(arr, dtype=dtype) 
 
-    answers = list(map(cast, [  
-      [[ 0, 0 ]],
-      [[ 0, 0 ]],
-      [[ 0, 1 ]],
-      [[ 1, 1 ]],
-      [[ 0, 2 ]],
-    ]))
+  cast = lambda arr: np.array(arr, dtype=dtype) 
 
-    for i in range(len(cases)):
-      case = cases[i]
-      result, = tinybrain.downsample.downsample_with_max_pooling(case, (2, 1))
-      assert np.all(result == answers[i])
+  answers = list(map(cast, [  
+    [[ 0, 0 ]],
+    [[ 0, 0 ]],
+    [[ 0, 1 ]],
+    [[ 1, 1 ]],
+    [[ 0, 2 ]],
+  ]))
 
-    answers = list(map(cast, [  
-      [[ 0 ], [ 0 ]],
-      [[ 0 ], [ 0 ]],
-      [[ 1 ], [ 0 ]],
-      [[ 1 ], [ 1 ]],
-      [[ 1 ], [ 2 ]],
-    ]))
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_max_pooling(case, (2, 1))
+    assert np.all(result == answers[i])
+
+  answers = list(map(cast, [  
+    [[ 0 ], [ 0 ]],
+    [[ 0 ], [ 0 ]],
+    [[ 1 ], [ 0 ]],
+    [[ 1 ], [ 1 ]],
+    [[ 1 ], [ 2 ]],
+  ]))
 
-    for i in range(len(cases)):
-      case = cases[i]
-      result, = tinybrain.downsample.downsample_with_max_pooling(case, (1, 2))
-      assert np.all(result == answers[i])
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_max_pooling(case, (1, 2))
+    assert np.all(result == answers[i])
 
   result, = tinybrain.downsample.downsample_with_max_pooling(image4x4x4, (2, 2, 2))
   answer = cast([
@@ -449,6 +449,57 @@ def test_downsample_max_pooling():
 
   assert np.all(result == answer)
 
+@pytest.mark.parametrize("dtype", [np.int8, np.float32])
+def test_downsample_min_pooling(dtype):
+  cases = [
+    np.array([ [ -1, 0 ], [ 0, 0 ] ], dtype=dtype), 
+    np.array([ [ 0, 0 ], [ 0, 0 ] ], dtype=dtype), 
+    np.array([ [ 0, 1 ], [ 0, 0 ] ], dtype=dtype),
+    np.array([ [ 0, 1 ], [ 1, 0 ] ], dtype=dtype),
+    np.array([ [ 0, 1 ], [ 0, 2 ] ], dtype=dtype)
+  ]
+
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_min_pooling(case, (1, 1))
+    assert np.all(result == cases[i])
+
+  answers = [ -1, 0, 0, 0, 0 ]
+
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_min_pooling(case, (2, 2))
+    assert result == answers[i]
+
+  cast = lambda arr: np.array(arr, dtype=dtype) 
+
+  answers = list(map(cast, [  
+    [[ -1, 0 ]],
+    [[ 0, 0 ]],
+    [[ 0, 0 ]],
+    [[ 0, 0 ]],
+    [[ 0, 1 ]],
+  ]))
+
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_min_pooling(case, (2, 1))
+    print(result)
+    assert np.all(result == answers[i])
+
+  answers = list(map(cast, [  
+    [[ -1 ], [ 0 ]],
+    [[ 0 ], [ 0 ]],
+    [[ 0 ], [ 0 ]],
+    [[ 0 ], [ 0 ]],
+    [[ 0 ], [ 0 ]],
+  ]))
+
+  for i in range(len(cases)):
+    case = cases[i]
+    result, = tinybrain.downsample.downsample_with_min_pooling(case, (1, 2))
+    assert np.all(result == answers[i])
+
 def test_countless3d():
   def test_all_cases(fn):
     alldifferent = [

tinybrain/downsample.py

@@ -154,11 +154,25 @@ def downsample_with_max_pooling(array, factor, num_mips=1):
   """
   results = []
   for mip in range(num_mips):
-    array = _downsample_with_max_pooling(array, factor)
+    array = _downsample_with(array, factor, fn=np.maximum)
     results.append(array)
   return results
 
-def _downsample_with_max_pooling(array, factor):
+def downsample_with_min_pooling(array, factor, num_mips=1):
+  """
+  Downsample by picking the minimum value within a
+  cuboid specified by factor. That is, a reduction factor
+  of 2x2 works by summarizing many 2x2 cuboids. If factor's 
+  length is smaller than array.shape, the remaining factors will
+  be filled with 1.
+  """
+  results = []
+  for mip in range(num_mips):
+    array = _downsample_with(array, factor, fn=np.minimum)
+    results.append(array)
+  return results
+
+def _downsample_with(array, factor, fn):
   """
   Downsample by picking the maximum value within a
   cuboid specified by factor. That is, a reduction factor
@@ -179,7 +193,7 @@ def _downsample_with_max_pooling(array, factor):
   output = sections[0].copy()
 
   for section in sections[1:]:
-    np.maximum(output, section, output)
+    fn(output, section, output)
 
   return output