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LSST Data Management Base Package
Public Member Functions | Properties | List of all members
lsst.skymap.tractInfo.TractInfo Class Reference
Inheritance diagram for lsst.skymap.tractInfo.TractInfo:
lsst.skymap.healpixSkyMap.HealpixTractInfo lsst.skymap.tractInfo.ExplicitTractInfo

Public Member Functions

def __init__ (self, id, tractBuilder, ctrCoord, vertexCoordList, tractOverlap, wcs)
 
def getSequentialPatchIndex (self, patchInfo)
 
def getSequentialPatchIndexFromPair (self, index)
 
def getPatchIndexPair (self, sequentialIndex)
 
def findPatch (self, coord)
 
def findPatchList (self, coordList)
 
def getBBox (self)
 
def getCtrCoord (self)
 
def getId (self)
 
def getNumPatches (self)
 
def getPatchBorder (self)
 
def getPatchInfo (self, index)
 
def getPatchInnerDimensions (self)
 
def getTractOverlap (self)
 
def getVertexList (self)
 
def getInnerSkyPolygon (self)
 
def getOuterSkyPolygon (self)
 
def getWcs (self)
 
def __str__ (self)
 
def __repr__ (self)
 
def __iter__ (self)
 
def __len__ (self)
 
def __getitem__ (self, index)
 
def contains (self, coord)
 

Properties

 bbox = property(getBBox)
 
 ctr_coord = property(getCtrCoord)
 
 tract_id = property(getId)
 
 num_patches = property(getNumPatches)
 
 patch_border = property(getPatchBorder)
 
 patch_inner_dimensions = property(getPatchInnerDimensions)
 
 tract_overlap = property(getTractOverlap)
 
 vertex_list = property(getVertexList)
 
 inner_sky_polygon = property(getInnerSkyPolygon)
 
 outer_sky_polygon = property(getOuterSkyPolygon)
 
 wcs = property(getWcs)
 

Detailed Description

Information about a tract in a SkyMap sky pixelization

Parameters
----------
id : `int`
    tract ID
tractBuilder : Subclass of `lsst.skymap.BaseTractBuilder`
    Object used to compute patch geometry.
ctrCoord : `lsst.geom.SpherePoint`
    ICRS sky coordinate of center of inner region of tract; also used as
    the CRVAL for the WCS.
vertexCoordList : `list` of `lsst.geom.SpherePoint`
    Vertices that define the boundaries of the inner region.
tractOverlap : `lsst.geom.Angle`
    Minimum overlap between adjacent sky tracts; this defines the minimum
    distance the tract extends beyond the inner region in all directions.
wcs : `lsst.afw.image.SkyWcs`
    WCS for tract. The reference pixel will be shifted as required so that
    the lower left-hand pixel (index 0,0) has pixel position 0.0, 0.0.

Notes
-----
The tract is subdivided into rectangular patches. Each patch has the
following properties:

- An inner region defined by an inner bounding box. The inner regions of
  the patches exactly tile the tract, and all inner regions have the same
  dimensions. The tract is made larger as required to make this work.

- An outer region defined by an outer bounding box. The outer region
  extends beyond the inner region by patchBorder pixels in all directions,
  except there is no border at the edges of the tract.
  Thus patches overlap each other but never extend off the tract.
  If you do not want any overlap between adjacent patches then set
  patchBorder to 0.

- An index that consists of a pair of integers:

  * 0 <= x index < numPatches[0]

  * 0 <= y index < numPatches[1]

  Patch 0,0 is at the minimum corner of the tract bounding box.

- It is not enforced that ctrCoord is the center of vertexCoordList, but
  SkyMap relies on it.

Definition at line 34 of file tractInfo.py.

Constructor & Destructor Documentation

◆ __init__()

def lsst.skymap.tractInfo.TractInfo.__init__ (   self,
  id,
  tractBuilder,
  ctrCoord,
  vertexCoordList,
  tractOverlap,
  wcs 
)

Reimplemented in lsst.skymap.tractInfo.ExplicitTractInfo, and lsst.skymap.healpixSkyMap.HealpixTractInfo.

Definition at line 82 of file tractInfo.py.

82 def __init__(self, id, tractBuilder, ctrCoord, vertexCoordList, tractOverlap, wcs):
83 self._id = id
84 self._ctrCoord = ctrCoord
85 self._vertexCoordList = tuple(vertexCoordList)
86 self._tractOverlap = tractOverlap
87 self._tractBuilder = tractBuilder
88
89 minBBox = self._minimumBoundingBox(wcs)
90 initialBBox, self._numPatches = self._tractBuilder.setupPatches(minBBox, wcs)
91 self._bbox, self._wcs = self._finalOrientation(initialBBox, wcs)
92

Member Function Documentation

◆ __getitem__()

def lsst.skymap.tractInfo.TractInfo.__getitem__ (   self,
  index 
)

Definition at line 393 of file tractInfo.py.

393 def __getitem__(self, index):
394 return self.getPatchInfo(index)
395

◆ __iter__()

def lsst.skymap.tractInfo.TractInfo.__iter__ (   self)

Definition at line 383 of file tractInfo.py.

383 def __iter__(self):
384 xNum, yNum = self.getNumPatches()
385 for y in range(yNum):
386 for x in range(xNum):
387 yield self.getPatchInfo(Index2D(x=x, y=y))
388

◆ __len__()

def lsst.skymap.tractInfo.TractInfo.__len__ (   self)

Definition at line 389 of file tractInfo.py.

389 def __len__(self):
390 xNum, yNum = self.getNumPatches()
391 return xNum*yNum
392

◆ __repr__()

def lsst.skymap.tractInfo.TractInfo.__repr__ (   self)

Definition at line 380 of file tractInfo.py.

380 def __repr__(self):
381 return "TractInfo(id=%s, ctrCoord=%s)" % (self._id, self._ctrCoord.getVector())
382

◆ __str__()

def lsst.skymap.tractInfo.TractInfo.__str__ (   self)

Definition at line 377 of file tractInfo.py.

377 def __str__(self):
378 return "TractInfo(id=%s)" % (self._id,)
379

◆ contains()

def lsst.skymap.tractInfo.TractInfo.contains (   self,
  coord 
) 
Does this tract contain the coordinate?

Definition at line 396 of file tractInfo.py.

396 def contains(self, coord):
397 """Does this tract contain the coordinate?"""
398 try:
399 pixel = self.getWcs().skyToPixel(coord)
400 except (lsst.pex.exceptions.DomainError, lsst.pex.exceptions.RuntimeError):
401 # Point must be way off the tract
402 return False
403 if not np.isfinite(pixel.getX()) or not np.isfinite(pixel.getY()):
404 # Point is definitely off the tract
405 return False
406 return self.getBBox().contains(geom.Point2I(pixel))
407
408
lsst.pex::exceptions::DomainError
Reports arguments outside the domain of an operation.
Definition: Runtime.h:57
lsst.pex::exceptions::RuntimeError
Reports errors that are due to events beyond the control of the program.
Definition: Runtime.h:104

◆ findPatch()

def lsst.skymap.tractInfo.TractInfo.findPatch (   self,
  coord 
) 
Find the patch containing the specified coord.

Parameters
----------
coord : `lsst.geom.SpherePoint`
    ICRS sky coordinate to search for.

Returns
-------
result : `lsst.skymap.PatchInfo`
    PatchInfo of patch whose inner bbox contains the specified coord

Raises
------
LookupError
    If coord is not in tract or we cannot determine the
    pixel coordinate (which likely means the coord is off the tract).

Definition at line 186 of file tractInfo.py.

186 def findPatch(self, coord):
187 """Find the patch containing the specified coord.
188
189 Parameters
190 ----------
191 coord : `lsst.geom.SpherePoint`
192 ICRS sky coordinate to search for.
193
194 Returns
195 -------
196 result : `lsst.skymap.PatchInfo`
197 PatchInfo of patch whose inner bbox contains the specified coord
198
199 Raises
200 ------
201 LookupError
202 If coord is not in tract or we cannot determine the
203 pixel coordinate (which likely means the coord is off the tract).
204 """
205 try:
206 pixel = self.wcs.skyToPixel(coord)
207 except (lsst.pex.exceptions.DomainError, lsst.pex.exceptions.RuntimeError):
208 # Point must be way off the tract
209 raise LookupError("Unable to determine pixel position for coordinate %s" % (coord,))
210 pixelInd = geom.Point2I(pixel)
211 if not self._bbox.contains(pixelInd):
212 raise LookupError("coord %s is not in tract %s" % (coord, self.tract_id))
213 # This should probably be the same as above because we only
214 # care about the INNER dimensions.
215 patchInd = tuple(int(pixelInd[i]/self.patch_inner_dimensions[i]) for i in range(2))
216 return self.getPatchInfo(patchInd)
217
lsst::geom::SpherePoint
Point in an unspecified spherical coordinate system.
Definition: SpherePoint.h:57

◆ findPatchList()

def lsst.skymap.tractInfo.TractInfo.findPatchList (   self,
  coordList 
) 
Find patches containing the specified list of coords.

Parameters
----------
coordList : `list` of `lsst.geom.SpherePoint`
    ICRS sky coordinates to search for.

Returns
-------
result : `list` of `lsst.skymap.PatchInfo`
    List of PatchInfo for patches that contain, or may contain, the
    specified region. The list will be empty if there is no overlap.

Notes
-----
**Warning:**

- This may give incorrect answers on regions that are larger than a
  tract.

- This uses a naive algorithm that may find some patches that do not
  overlap the region (especially if the region is not a rectangle
  aligned along patch x,y).

Definition at line 218 of file tractInfo.py.

218 def findPatchList(self, coordList):
219 """Find patches containing the specified list of coords.
220
221 Parameters
222 ----------
223 coordList : `list` of `lsst.geom.SpherePoint`
224 ICRS sky coordinates to search for.
225
226 Returns
227 -------
228 result : `list` of `lsst.skymap.PatchInfo`
229 List of PatchInfo for patches that contain, or may contain, the
230 specified region. The list will be empty if there is no overlap.
231
232 Notes
233 -----
234 **Warning:**
235
236 - This may give incorrect answers on regions that are larger than a
237 tract.
238
239 - This uses a naive algorithm that may find some patches that do not
240 overlap the region (especially if the region is not a rectangle
241 aligned along patch x,y).
242 """
243 box2D = geom.Box2D()
244 for coord in coordList:
245 try:
246 pixelPos = self.wcs.skyToPixel(coord)
247 except (lsst.pex.exceptions.DomainError, lsst.pex.exceptions.RuntimeError):
248 # the point is so far off the tract that its pixel position cannot be computed
249 continue
250 box2D.include(pixelPos)
251 bbox = geom.Box2I(box2D)
252 bbox.grow(self.getPatchBorder())
253 bbox.clip(self._bbox)
254 if bbox.isEmpty():
255 return ()
256
257 llPatchInd = tuple(int(bbox.getMin()[i]/self.patch_inner_dimensions[i]) for i in range(2))
258 urPatchInd = tuple(int(bbox.getMax()[i]/self.patch_inner_dimensions[i]) for i in range(2))
259 return tuple(self.getPatchInfo((xInd, yInd))
260 for xInd in range(llPatchInd[0], urPatchInd[0]+1)
261 for yInd in range(llPatchInd[1], urPatchInd[1]+1))
262
lsst::geom::Box2D
A floating-point coordinate rectangle geometry.
Definition: Box.h:413
lsst::geom::Box2I
An integer coordinate rectangle.
Definition: Box.h:55

◆ getBBox()

def lsst.skymap.tractInfo.TractInfo.getBBox (   self) 
Get bounding box of tract (as an geom.Box2I)

Definition at line 263 of file tractInfo.py.

263 def getBBox(self):
264 """Get bounding box of tract (as an geom.Box2I)
265 """
266 return geom.Box2I(self._bbox)
267

◆ getCtrCoord()

def lsst.skymap.tractInfo.TractInfo.getCtrCoord (   self) 
Get ICRS sky coordinate of center of tract
(as an lsst.geom.SpherePoint)

Definition at line 270 of file tractInfo.py.

270 def getCtrCoord(self):
271 """Get ICRS sky coordinate of center of tract
272 (as an lsst.geom.SpherePoint)
273 """
274 return self._ctrCoord
275

◆ getId()

def lsst.skymap.tractInfo.TractInfo.getId (   self) 
Get ID of tract

Definition at line 278 of file tractInfo.py.

278 def getId(self):
279 """Get ID of tract
280 """
281 return self._id
282

◆ getInnerSkyPolygon()

def lsst.skymap.tractInfo.TractInfo.getInnerSkyPolygon (   self) 
Get inner on-sky region as a sphgeom.ConvexPolygon.

Definition at line 350 of file tractInfo.py.

350 def getInnerSkyPolygon(self):
351 """Get inner on-sky region as a sphgeom.ConvexPolygon.
352 """
353 skyUnitVectors = [sp.getVector() for sp in self.getVertexList()]
354 return ConvexPolygon.convexHull(skyUnitVectors)
355

◆ getNumPatches()

def lsst.skymap.tractInfo.TractInfo.getNumPatches (   self) 
Get the number of patches in x, y.

Returns
-------
result : `lsst.skymap.Index2D`
    The number of patches in x, y

Definition at line 285 of file tractInfo.py.

285 def getNumPatches(self):
286 """Get the number of patches in x, y.
287
288 Returns
289 -------
290 result : `lsst.skymap.Index2D`
291 The number of patches in x, y
292 """
293 return self._numPatches
294

◆ getOuterSkyPolygon()

def lsst.skymap.tractInfo.TractInfo.getOuterSkyPolygon (   self) 
Get outer on-sky region as a sphgeom.ConvexPolygon

Definition at line 358 of file tractInfo.py.

358 def getOuterSkyPolygon(self):
359 """Get outer on-sky region as a sphgeom.ConvexPolygon
360 """
361 return makeSkyPolygonFromBBox(bbox=self.getBBox(), wcs=self.getWcs())
362
lsst.skymap.detail.utils.makeSkyPolygonFromBBox
def makeSkyPolygonFromBBox(bbox, wcs)
Definition: utils.py:61

◆ getPatchBorder()

def lsst.skymap.tractInfo.TractInfo.getPatchBorder (   self)

Definition at line 297 of file tractInfo.py.

297 def getPatchBorder(self):
298 return self._tractBuilder.getPatchBorder()
299

◆ getPatchIndexPair()

def lsst.skymap.tractInfo.TractInfo.getPatchIndexPair (   self,
  sequentialIndex 
) 
Convert sequential index into patch index (x,y) pair.

Parameters
----------
sequentialIndex : `int`

Returns
-------
x, y : `lsst.skymap.Index2D`

Definition at line 173 of file tractInfo.py.

173 def getPatchIndexPair(self, sequentialIndex):
174 """Convert sequential index into patch index (x,y) pair.
175
176 Parameters
177 ----------
178 sequentialIndex : `int`
179
180 Returns
181 -------
182 x, y : `lsst.skymap.Index2D`
183 """
184 return self._tractBuilder.getPatchIndexPair(sequentialIndex)
185

◆ getPatchInfo()

def lsst.skymap.tractInfo.TractInfo.getPatchInfo (   self,
  index 
) 
Return information for the specified patch.

Parameters
----------
index : `typing.NamedTuple` ['x': `int`, 'y': `int`]
    Index of patch, as a pair of ints;
    or a sequential index as returned by getSequentialPatchIndex;
    negative values are not supported.

Returns
-------
result : `lsst.skymap.PatchInfo`
    The patch info for that index.

Raises
------
IndexError
    If index is out of range.

Definition at line 302 of file tractInfo.py.

302 def getPatchInfo(self, index):
303 """Return information for the specified patch.
304
305 Parameters
306 ----------
307 index : `typing.NamedTuple` ['x': `int`, 'y': `int`]
308 Index of patch, as a pair of ints;
309 or a sequential index as returned by getSequentialPatchIndex;
310 negative values are not supported.
311
312 Returns
313 -------
314 result : `lsst.skymap.PatchInfo`
315 The patch info for that index.
316
317 Raises
318 ------
319 IndexError
320 If index is out of range.
321 """
322 return self._tractBuilder.getPatchInfo(index, self._wcs)
323

◆ getPatchInnerDimensions()

def lsst.skymap.tractInfo.TractInfo.getPatchInnerDimensions (   self) 
Get dimensions of inner region of the patches (all are the same)

Definition at line 324 of file tractInfo.py.

324 def getPatchInnerDimensions(self):
325 """Get dimensions of inner region of the patches (all are the same)
326 """
327 return self._tractBuilder.getPatchInnerDimensions()
328

◆ getSequentialPatchIndex()

def lsst.skymap.tractInfo.TractInfo.getSequentialPatchIndex (   self,
  patchInfo 
) 
Return a single integer that uniquely identifies
the given patch within this tract.

Parameters
----------
patchInfo : `lsst.skymap.PatchInfo`

Returns
-------
sequentialIndex : `int`

Definition at line 145 of file tractInfo.py.

145 def getSequentialPatchIndex(self, patchInfo):
146 """Return a single integer that uniquely identifies
147 the given patch within this tract.
148
149 Parameters
150 ----------
151 patchInfo : `lsst.skymap.PatchInfo`
152
153 Returns
154 -------
155 sequentialIndex : `int`
156 """
157 return self._tractBuilder.getSequentialPatchIndex(patchInfo)
158

◆ getSequentialPatchIndexFromPair()

def lsst.skymap.tractInfo.TractInfo.getSequentialPatchIndexFromPair (   self,
  index 
) 
Return a single integer that uniquely identifies
the patch index within the tract.

Parameters
----------
index : `lsst.skymap.Index2D`

Returns
-------
sequentialIndex : `int`

Definition at line 159 of file tractInfo.py.

159 def getSequentialPatchIndexFromPair(self, index):
160 """Return a single integer that uniquely identifies
161 the patch index within the tract.
162
163 Parameters
164 ----------
165 index : `lsst.skymap.Index2D`
166
167 Returns
168 -------
169 sequentialIndex : `int`
170 """
171 return self._tractBuilder.getSequentialPatchIndexFromPair(index)
172

◆ getTractOverlap()

def lsst.skymap.tractInfo.TractInfo.getTractOverlap (   self) 
Get minimum overlap of adjacent sky tracts.

Definition at line 331 of file tractInfo.py.

331 def getTractOverlap(self):
332 """Get minimum overlap of adjacent sky tracts.
333 """
334 return self._tractOverlap
335

◆ getVertexList()

def lsst.skymap.tractInfo.TractInfo.getVertexList (   self) 
Get list of ICRS sky coordinates of vertices that define the
boundary of the inner region.

Notes
-----
**warning:** this is not a deep copy.

Definition at line 338 of file tractInfo.py.

338 def getVertexList(self):
339 """Get list of ICRS sky coordinates of vertices that define the
340 boundary of the inner region.
341
342 Notes
343 -----
344 **warning:** this is not a deep copy.
345 """
346 return self._vertexCoordList
347

◆ getWcs()

def lsst.skymap.tractInfo.TractInfo.getWcs (   self) 
Get WCS of tract.

Returns
-------
wcs : `lsst.afw.geom.SkyWcs`
    The WCS of this tract

Definition at line 365 of file tractInfo.py.

365 def getWcs(self):
366 """Get WCS of tract.
367
368 Returns
369 -------
370 wcs : `lsst.afw.geom.SkyWcs`
371 The WCS of this tract
372 """
373 return self._wcs
374
lsst::afw::geom::SkyWcs
A 2-dimensional celestial WCS that transform pixels to ICRS RA/Dec, using the LSST standard for pixel...
Definition: SkyWcs.h:117

Property Documentation

◆ bbox

lsst.skymap.tractInfo.TractInfo.bbox = property(getBBox)
static

Definition at line 268 of file tractInfo.py.

◆ ctr_coord

lsst.skymap.tractInfo.TractInfo.ctr_coord = property(getCtrCoord)
static

Definition at line 276 of file tractInfo.py.

◆ inner_sky_polygon

lsst.skymap.tractInfo.TractInfo.inner_sky_polygon = property(getInnerSkyPolygon)
static

Definition at line 356 of file tractInfo.py.

◆ num_patches

lsst.skymap.tractInfo.TractInfo.num_patches = property(getNumPatches)
static

Definition at line 295 of file tractInfo.py.

◆ outer_sky_polygon

lsst.skymap.tractInfo.TractInfo.outer_sky_polygon = property(getOuterSkyPolygon)
static

Definition at line 363 of file tractInfo.py.

◆ patch_border

lsst.skymap.tractInfo.TractInfo.patch_border = property(getPatchBorder)
static

Definition at line 300 of file tractInfo.py.

◆ patch_inner_dimensions

lsst.skymap.tractInfo.TractInfo.patch_inner_dimensions = property(getPatchInnerDimensions)
static

Definition at line 329 of file tractInfo.py.

◆ tract_id

lsst.skymap.tractInfo.TractInfo.tract_id = property(getId)
static

Definition at line 283 of file tractInfo.py.

◆ tract_overlap

lsst.skymap.tractInfo.TractInfo.tract_overlap = property(getTractOverlap)
static

Definition at line 336 of file tractInfo.py.

◆ vertex_list

lsst.skymap.tractInfo.TractInfo.vertex_list = property(getVertexList)
static

Definition at line 348 of file tractInfo.py.

◆ wcs

lsst.skymap.tractInfo.TractInfo.wcs = property(getWcs)
static

Definition at line 375 of file tractInfo.py.

The documentation for this class was generated from the following file:
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