public intg narrow_into(ref idxspec dst, int d, intg s, intg o)
{
if (ndim <= 0)
{
throw new Exception("cannot narrow a scalar");
}
if ((d < 0) || (d >= ndim))
{
throw new Exception("narrow: illegal dimension index " + d + " in " + this);
}
if ((o < 0) || (s < 1) || (s + o > dim[d]))
{
throw new Exception("trying to narrow dimension " + d + " to size " + s
+ " starting at offset " + o + " in " + this);
}
// this preserves the dim/mod arrays if dst == this
dst.setndim(ndim);
dst.offset = offset + o * mod[d];
for (int j = 0; j < ndim; j++)
{
dst.dim[j] = dim[j];
dst.mod[j] = mod[j];
}
dst.dim[d] = s;
return(s);
}
// select, narrow, unfold, etc
// Each function has 3 version:
// 1. XXX_into: which writes the result
// into an existing idxspec apssed as argument.
// 2. XXX_inplace: writes into the current idxspec
// 3. XXX: creates a new idxspec and returns it.
public intg select_into(ref idxspec dst, int d, intg n)
{
if (ndim <= 0)
{
throw new Exception("cannot select an empty idx idx that is a scalar ("
+ this + ")");
}
if ((n < 0) || (n >= dim[d]))
{
throw new Exception("trying to select layer " + n
+ " of dimension " + d + " which is of size "
+ dim[d] + " in idx " + this);
}
// this preserves the dim/mod arrays if dst == this
dst.setndim(ndim - 1);
dst.offset = offset + (n * mod[d]);
if (ndim - 1 > 0)
{ // dim and mod don't exist for idx0
for (int j = 0; j < d; j++)
{
dst.dim[j] = dim[j];
dst.mod[j] = mod[j];
}
for (int j = d; j < ndim - 1; j++)
{
dst.dim[j] = dim[j + 1];
dst.mod[j] = mod[j + 1];
}
}
return(n);
}
////////////////////////////////////////////////////////////////
// unfold
// d: dimension; k: kernel size; s: stride.
public intg unfold_into(ref idxspec dst, int d, intg k, intg s)
{
intg ns; // size of newly created dimension
String err = "";
if (ndim <= 0)
{
err += "cannot unfold an idx of maximum order";
}
else if ((d < 0) || (d >= ndim))
{
err += "unfold: illegal dimension index";
}
else if ((k < 1) || (s < 1))
{
err += "unfold: kernel and stride must be >= 1";
}
ns = 1 + (dim[d] - k) / s;
if (!String.IsNullOrWhiteSpace(err) && ((ns <= 0) || (dim[d] != s * (ns - 1) + k)))
{
err += "unfold: kernel and stride incompatible with size";
}
if (!String.IsNullOrWhiteSpace(err))
{
throw new Exception(err + ", while unfolding dimension " + d + " to size " + k
+ " with step " + s + " from idx " + this + " into idx "
+ dst);
}
// this preserves the dim/mod arrays if dst == this
dst.setndim(ndim + 1);
dst.offset = offset;
for (int i = 0; i < ndim; i++)
{
dst.dim[i] = dim[i];
dst.mod[i] = mod[i];
}
dst.dim[ndim] = k;
dst.mod[ndim] = mod[d];
dst.dim[d] = ns;
dst.mod[d] = mod[d] * s;
return(ns);
}
////////////////////////////////////////////////////////////////
// transpose
// tranpose two dimensions into pre-existing idxspec
public int transpose_into(ref idxspec dst, int d1, int d2)
{
if ((d1 < 0) || (d1 >= ndim) || (d2 < 0) || (d2 >= ndim))
{
throw new Exception("illegal transpose of dimension " + d1
+ " to dimension " + d2);
}
// this preserves the dim/mod arrays if dst == this
dst.setndim(ndim);
dst.offset = offset;
for (int j = 0; j < ndim; j++)
{
dst.dim[j] = dim[j];
dst.mod[j] = mod[j];
}
intg tmp;
// we do this in case dst = this
tmp = dim[d1]; dst.dim[d1] = dim[d2]; dst.dim[d2] = tmp;
tmp = mod[d1]; dst.mod[d1] = mod[d2]; dst.mod[d2] = tmp;
return(ndim);
}
// tranpose all dims with a permutation vector
public int transpose_into(ref idxspec dst, int[] p)
{
for (int i = 0; i < ndim; i++)
{
if ((p[i] < 0) || (p[i] >= ndim))
{
throw new Exception("illegal transpose of dimensions");
}
}
dst.setndim(ndim);
dst.offset = offset;
if (dst == this)
{
// we need temp storage if done in place
intg[] tmpdim = new intg[Global.MAXDIMS];
intg[] tmpmod = new intg[Global.MAXDIMS];
for (int j = 0; j < ndim; j++)
{
tmpdim[j] = dim[p[j]];
tmpmod[j] = mod[p[j]];
}
for (int j = 0; j < ndim; j++)
{
dst.dim[j] = tmpdim[j];
dst.mod[j] = tmpmod[j];
}
}
else
{
// not in place
for (int j = 0; j < ndim; j++)
{
dst.dim[j] = dim[p[j]];
dst.mod[j] = mod[p[j]];
}
}
return(ndim);
}