internal static Function Conv(this Function input,
int[] filterShape,
int filterCount,
int[] filterStride,
Padding padding, // TODO: Consider if padding should be decided pr. dimension.
CNTKDictionary weightInitializer,
CNTKDictionary biasInitializer,
DeviceDescriptor device,
DataType dataType)
{
var weights = new Parameter(NDShape.CreateNDShape(filterShape), dataType,
weightInitializer, device);
var strideShape = NDShape.CreateNDShape(filterStride);
// Currently, only sharing=true is supported by CNTK. So these are hardcoded.
// sharing dimensions follows stride dimensions. 1D, 2D, 3D, etc.
var sharing = CntkUtilities.CreateFilledBoolVector(filterStride.Length, true);
// Padding dimensions follows stride dimensions. 1D, 2D, 3D, etc.
var usePadding = padding.ToBoolean();
var autoPadding = CntkUtilities.CreateFilledBoolVector(filterStride.Length, usePadding);
// TODO: Consider if we want to surface the additional options for Convolution:
// - dilation
// - reductionRank
// - groups
// - maxTempMemSizeInSamples
// Default for dilation seems to be a shape of size (1) with value 1
var dilation = NDShape.CreateNDShape(new[] { 1 });
// Following are defaults extrapolated from CNTK code
var reductionRank = 1u;
var groups = 1u;
var maxTempMemSizeInSamples = 0u;
var sequential = false;
var result = CNTKLib.Convolution(
weights, input, strideShape, sharing, autoPadding,
dilation, reductionRank, groups, maxTempMemSizeInSamples, sequential);
if (biasInitializer != null)
{
// Bias dimensions should be defined for filter dimensions.
// For instance for 2D case: (1, 1, filterChannels).
var biasShape = filterStride.Select(s => 1).ToList();
biasShape.Add(filterCount);
var bias = new Parameter(NDShape.CreateNDShape(biasShape.ToArray()),
dataType, biasInitializer, device);
result = CNTKLib.Plus(result, bias);
}
return(result);
}
public static Function MaxPool2D(this Function input,
ValueTuple <int, int> poolShape,
ValueTuple <int, int> strideShape,
Padding padding)
{
var usePadding = padding.ToBoolean();
var poolSizes = new int[] { poolShape.Item1, poolShape.Item2 };
var strideSizes = new int[] { strideShape.Item1, strideShape.Item2 };
var paddingSizes = new bool[] { usePadding, usePadding };
return(CNTKLib.Pooling(input,
PoolingType.Max,
poolSizes,
strideSizes,
paddingSizes));
}
public static Function MaxPool1D(this Function input,
int poolShape,
int strideShape,
Padding padding)
{
var usePadding = padding.ToBoolean();
var poolSizes = new int[] { poolShape };
var strideSizes = new int[] { strideShape };
var paddingSizes = new bool[] { usePadding };
return(CNTKLib.Pooling(input,
PoolingType.Max,
poolSizes,
strideSizes,
paddingSizes));
}
