Class FastFinder¶

Defined in File FastFinder.h

Nested Relationships¶

Nested Types¶

Class FastFinder::Iterator

Class Documentation¶

class FastFinder¶

Fast locator in starlists.

This is an auxillary class for matching objects from starlists. It allows to locate rapidly the closest objects from a given position. The very simple strategy is to sort objects according to 1 coordinate x, and to build an index that allows to select the objects with the x coordinate inside an interval. Then every slice in x is sorted according to y, which enables a fast scan inside a x slice. listMatchCollect takes about 10ms (PC 450 MHz, optimized “-O4”) for a match between lists of about 2000 objects each, which is fast enough for our needs. The same “locator” is used in listMatchupShift, to avoid scanning the whole input lists. Timing on listMatchCollect and listMatchupShift indicates a gain in speed by more than one order of magnitude after implementation of this FastFinder.

Public Functions

FastFinder(const BaseStarList &list, const unsigned nXSlice = 100)¶: Constructor.

std::shared_ptr<const BaseStar> lsst::jointcal::FastFinder::findClosest(const Point & where, const double maxDist, bool(*SkipIt)(const BaseStar &) = nullptr) const: Find the closest with some rejection capability.

std::shared_ptr<const BaseStar> lsst::jointcal::FastFinder::secondClosest(const Point & where, const double maxDist, std::shared_ptr< const BaseStar > & closest, bool(*SkipIt)(const BaseStar &) = nullptr) const

void dump() const¶: mostly for debugging

Iterator beginScan(const Point &where, double maxDist) const¶

void findRangeInSlice(const int iSlice, const double yStart, const double yEnd, pstar &start, pstar &end) const¶

pstar locateYStart(pstar begin, pstar end, double yVal) const¶

pstar locateYEnd(pstar begin, pstar end, double yVal) const¶

Public Members

decltype(stars) typedef ::value_type lsst::jointcal::FastFinder::stars_element

decltype(stars) typedef ::const_iterator lsst::jointcal::FastFinder::pstar

const BaseStarList baselist¶

unsigned count¶

std::vector<std::shared_ptr<const BaseStar>> stars¶

unsigned nslice¶

std::vector<unsigned> index¶

double xmin¶

double xmax¶

double xstep¶

class Iterator¶

Iterator meant to traverse objects within some limiting distance. Initializer is beginScan and end condition is (*it == NULL). Used by findClosest & co.