|
casa
$Rev:20696$
|
|
casa
$Rev:20696$
|
define a (start,length,increment) along an axis More...
#include <Slice.h>
Public Member Functions | |
| Slice () | |
| The entire range of indices on the axis is desired. | |
| Slice (size_t Start, size_t Length=1, size_t Inc=1) | |
| Create a Slice with a given start, length, and increment. | |
| Slice (size_t Start, size_t End, size_t Inc, Bool endIsLength) | |
| Create a Slice with a given start, end or length, and increment. | |
| Bool | all () const |
| Was the entire range of indices on this axis selected? | |
| size_t | start () const |
| Report the selected starting position. | |
| size_t | length () const |
| Report the defined length. | |
| size_t | inc () const |
| Report the defined increment. | |
| size_t | end () const |
| Attempt to report the last element of the slice. | |
Static Public Member Functions | |
| static IPosition | checkSlices (Vector< Vector< Slice > > &slices, Slicer &first, const IPosition &shape) |
| Check a vector of slices. | |
Private Attributes | |
| size_t | startp |
| ssize_t | incp |
| size_t | lengthp |
define a (start,length,increment) along an axis
<h3>Synopsis</h3>
A "slice" (aka Section) is a a regular sub-Array (and ultimately sub-Image)
that is defined by defining a (start,length,increment) for each axis in
the array. That is, the output array's axis is of size "length", and the
elements are sampled by stepping along the input array in strides of
"increment".
<br><strong>Warning:</strong><em>
The "length" is the length of the OUTPUT array, the output length
is NOT divided by the increment/stride;
</em><br>
If increment is not defined, then it defaults to one.
(Increment, if defined, must be >= 1). If length
is not defined, then it defaults to a length of one also (i.e. just the pixel
"start"). If start is also undefined, then all pixels along this axis are
chosen. This class deprecates the "_" (IndexRange) class, which had a failed
syntax and used (start,end,increment) which is generally less convenient.
Some simple examples follow:
Vector<Int> vi(100); // Vector of length 100; //..\. // Copy odd values onto even values vi(Slice(0,50,2)) = vi(Slice(1,50,2)); Matrix<float> mf(100,50), smallMf; smallMf.reference(mf(Slice(0,10,10), Slice(0,5,10))); // smallMF is now a "dezoomed" (every 10th pix) // refference to mf. Of course we could also // make it a copy by using assignment; e.g: smallMf.resize(0,0); // Make it so it will "size to fit" smallMf = mf(Slice(0,10,10), Slice(0,5,10));
As shown above, normally Slices will normally be used as temporaries, but they may also be put into variables if desired (the default copy constructors and assignment operators suffice for this class).
While it will be unusual for a user to want this, a zero-length slice is allowable.
Another way to produce a slice from any of the Array classes is to use SomeArray(blc,trc,inc) where blc,trc,inc are IPositions. This is described in the documentation for Array<T>.
| casa::Slice::Slice | ( | ) | [inline] |
| casa::Slice::Slice | ( | size_t | Start, |
| size_t | Length = 1, |
||
| size_t | Inc = 1 |
||
| ) | [inline] |
Create a Slice with a given start, length, and increment.
The latter two default to one if not given.
Definition at line 146 of file Slice.h.
References DebugAssert, and incp.
| casa::Slice::Slice | ( | size_t | Start, |
| size_t | End, | ||
| size_t | Inc, | ||
| Bool | endIsLength | ||
| ) | [inline] |
Create a Slice with a given start, end or length, and increment.
If endIsLength=False, end is interpreted as length.
Definition at line 155 of file Slice.h.
References DebugAssert, and incp.
| Bool casa::Slice::all | ( | ) | const [inline] |
| size_t casa::Slice::end | ( | ) | const [inline] |
| size_t casa::Slice::inc | ( | ) | const [inline] |
| size_t casa::Slice::length | ( | ) | const [inline] |
| size_t casa::Slice::start | ( | ) | const [inline] |
ssize_t casa::Slice::incp [private] |
size_t casa::Slice::lengthp [private] |
size_t casa::Slice::startp [private] |
1.8.0