private void _inferMissingDimension(ref Shape shape)
{
var indexOfNegOne = -1;
int product = 1;
for (int i = 0; i < shape.NDim; i++)
{
if (shape[i] == -1)
{
if (indexOfNegOne != -1)
{
throw new ArgumentException("Only allowed to pass one shape dimension as -1");
}
indexOfNegOne = i;
}
else
{
product *= shape[i];
}
}
if (indexOfNegOne == -1)
{
return;
}
if (this.IsBroadcasted)
{
/* //TODO: the following case needs to be handled.
* a = np.arange(4).reshape(1,2,2)
* print(a.strides)
*
* b = np.broadcast_to(a, (2,2,2))
* print(b.strides)
*
* c = np.reshape(b, (2, -1))
* print(c.strides)
*
* c = np.reshape(b, (-1, 2))
* print(c.strides)
*
* (16, 8, 4)
* (0, 8, 4)
* (0, 4) //here it handles broadcast
* (8, 4) //here can be seen that numpy performs a copy
*/
//var originalReshaped = np.broadcast_to(this.BroadcastInfo.OriginalShape.Reshape(new int[] { this.BroadcastInfo.OriginalShape.size }), (Shape) new int[] { this.size });
throw new NotSupportedException("Reshaping a broadcasted array with a -1 (unknown) dimension is not supported.");
}
int missingValue = this.size / product;
if (missingValue * product != this.size)
{
throw new ArgumentException("Bad shape: missing dimension would have to be non-integer");
}
shape.dimensions[indexOfNegOne] = missingValue;
var strides = shape.strides;
var dimensions = shape.dimensions;
if (indexOfNegOne == strides.Length - 1)
{
strides[strides.Length - 1] = 1;
}
for (int idx = indexOfNegOne; idx >= 1; idx--)
{
strides[idx - 1] = strides[idx] * dimensions[idx];
}
shape.ComputeHashcode();
}