本文整理汇总了Python中qgis.core.QgsDistanceArea类的典型用法代码示例。如果您正苦于以下问题:Python QgsDistanceArea类的具体用法?Python QgsDistanceArea怎么用?Python QgsDistanceArea使用的例子?那么恭喜您, 这里精选的类代码示例或许可以为您提供帮助。
在下文中一共展示了QgsDistanceArea类的15个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于系统推荐出更棒的Python代码示例。
示例1: nearest_neighbour_analysis
def nearest_neighbour_analysis(self, vlayer):
vprovider = vlayer.dataProvider()
sumDist = 0.00
distance = QgsDistanceArea()
A = vlayer.extent()
A = float(A.width() * A.height())
index = ftools_utils.createIndex(vprovider)
nFeat = vprovider.featureCount()
nElement = 0
if nFeat > 0:
self.emit(SIGNAL("runStatus(PyQt_PyObject)"), 0)
self.emit(SIGNAL("runRange(PyQt_PyObject)"), (0, nFeat))
feat = QgsFeature()
neighbour = QgsFeature()
fit = vprovider.getFeatures()
while fit.nextFeature(feat):
neighbourID = index.nearestNeighbor(feat.geometry().asPoint(), 2)[1]
vprovider.getFeatures(QgsFeatureRequest().setFilterFid(neighbourID).setSubsetOfAttributes([])).nextFeature(neighbour)
nearDist = distance.measureLine(neighbour.geometry().asPoint(), feat.geometry().asPoint())
sumDist += nearDist
nElement += 1
self.emit(SIGNAL("runStatus(PyQt_PyObject)"), nElement)
nVal = vprovider.featureCount()
do = float(sumDist) / nVal
de = float(0.5 / math.sqrt(nVal / A))
d = float(do / de)
SE = float(0.26136 / math.sqrt((nVal * nVal) / A))
zscore = float((do - de) / SE)
lstStats = []
lstStats.append(self.tr("Observed mean distance:") + unicode(do))
lstStats.append(self.tr("Expected mean distance:") + unicode(de))
lstStats.append(self.tr("Nearest neighbour index:") + unicode(d))
lstStats.append(self.tr("N:") + unicode(nVal))
lstStats.append(self.tr("Z-Score:") + unicode(zscore))
return (lstStats, [])
示例2: testMeasurePolygon
def testMeasurePolygon(self):
# +-+-+
# | |
# + +-+
# | |
# +-+
polygon = QgsGeometry.fromPolygon(
[
[
QgsPoint(0, 0),
QgsPoint(1, 0),
QgsPoint(1, 1),
QgsPoint(2, 1),
QgsPoint(2, 2),
QgsPoint(0, 2),
QgsPoint(0, 0),
]
]
)
da = QgsDistanceArea()
area = da.measure(polygon)
assert area == 3, "Expected:\n%f\nGot:\n%f\n" % (3, area)
perimeter = da.measurePerimeter(polygon)
assert perimeter == 8, "Expected:\n%f\nGot:\n%f\n" % (8, perimeter)
示例3: regularMatrix
def regularMatrix(self, inLayer, inField, targetLayer, targetField,
nPoints, progress):
features = vector.features(inLayer)
total = 100.0 / len(features) if len(features) > 0 else 1
targetIdx = targetLayer.fieldNameIndex(targetField)
first = True
distArea = QgsDistanceArea()
index = vector.spatialindex(targetLayer)
for current, inFeat in enumerate(features):
inGeom = inFeat.geometry()
if first:
featList = index.nearestNeighbor(inGeom.asPoint(), nPoints)
first = False
data = ['ID']
request = QgsFeatureRequest().setFilterFids(featList).setSubsetOfAttributes([targetIdx])
for f in targetLayer.getFeatures(request):
data.append(unicode(f[targetField]))
self.writer.addRecord(data)
data = [unicode(inFeat[inField])]
for f in targetLayer.getFeatures(request):
outGeom = f.geometry()
dist = distArea.measureLine(inGeom.asPoint(), outGeom.asPoint())
data.append(unicode(float(dist)))
self.writer.addRecord(data)
progress.setPercentage(int(current * total))
示例4: prepareAlgorithm
def prepareAlgorithm(self, parameters, context, feedback):
source = self.parameterAsSource(parameters, 'INPUT', context)
mapping = self.parameterAsFieldsMapping(parameters, self.FIELDS_MAPPING, context)
self.fields = QgsFields()
self.expressions = []
da = QgsDistanceArea()
da.setSourceCrs(source.sourceCrs())
da.setEllipsoid(context.project().ellipsoid())
# create an expression context using thread safe processing context
self.expr_context = self.createExpressionContext(parameters, context, source)
for field_def in mapping:
self.fields.append(QgsField(name=field_def['name'],
type=field_def['type'],
typeName="",
len=field_def.get('length', 0),
prec=field_def.get('precision', 0)))
expression = QgsExpression(field_def['expression'])
expression.setGeomCalculator(da)
expression.setDistanceUnits(context.project().distanceUnits())
expression.setAreaUnits(context.project().areaUnits())
if expression.hasParserError():
raise QgsProcessingException(
self.tr(u'Parser error in expression "{}": {}')
.format(str(expression.expression()),
str(expression.parserErrorString())))
self.expressions.append(expression)
return True
示例5: regularMatrix
def regularMatrix(self, inLayer, inField, targetLayer, targetField,
nPoints, progress):
index = vector.spatialindex(targetLayer)
inIdx = inLayer.fields().lookupField(inField)
distArea = QgsDistanceArea()
first = True
features = vector.features(inLayer)
total = 100.0 / len(features)
for current, inFeat in enumerate(features):
inGeom = inFeat.geometry()
inID = str(inFeat.attributes()[inIdx])
featList = index.nearestNeighbor(inGeom.asPoint(), nPoints)
if first:
first = False
data = ['ID']
for i in range(len(featList)):
data.append('DIST_{0}'.format(i + 1))
self.writer.addRecord(data)
data = [inID]
for i in featList:
request = QgsFeatureRequest().setFilterFid(i)
outFeat = next(targetLayer.getFeatures(request))
outGeom = outFeat.geometry()
dist = distArea.measureLine(inGeom.asPoint(),
outGeom.asPoint())
data.append(str(float(dist)))
self.writer.addRecord(data)
progress.setPercentage(int(current * total))
示例6: measurePerimeter
def measurePerimeter(geom):
measure = QgsDistanceArea()
value = 0.00
polygon = geom.asPolygon()
for line in polygon:
value += measure.measureLine(line)
return value
示例7: loopThruPolygons
def loopThruPolygons(self, inLayer, numRand, design):
sProvider = inLayer.dataProvider()
sFeat = QgsFeature()
sGeom = QgsGeometry()
sPoints = []
if design == self.tr("field"):
index = sProvider.fieldNameIndex(numRand)
count = 10.00
add = 60.00 / sProvider.featureCount()
sFit = sProvider.getFeatures()
featureErrors = []
while sFit.nextFeature(sFeat):
sGeom = sFeat.geometry()
if design == self.tr("density"):
sDistArea = QgsDistanceArea()
value = int(round(numRand * sDistArea.measure(sGeom)))
elif design == self.tr("field"):
sAtMap = sFeat.attributes()
try:
value = int(sAtMap[index])
except (ValueError,TypeError):
featureErrors.append(sFeat)
continue
else:
value = numRand
sExt = sGeom.boundingBox()
sPoints.extend(self.simpleRandom(value, sGeom, sExt.xMinimum(), sExt.xMaximum(), sExt.yMinimum(), sExt.yMaximum()))
count = count + add
self.progressBar.setValue(count)
return sPoints, featureErrors
示例8: processAlgorithm
def processAlgorithm(self, parameters, context, feedback):
source = self.parameterAsSource(parameters, self.INPUT, context)
layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
field_name = self.parameterAsString(parameters, self.FIELD_NAME, context)
field_type = self.TYPES[self.parameterAsEnum(parameters, self.FIELD_TYPE, context)]
width = self.parameterAsInt(parameters, self.FIELD_LENGTH, context)
precision = self.parameterAsInt(parameters, self.FIELD_PRECISION, context)
new_field = self.parameterAsBool(parameters, self.NEW_FIELD, context)
formula = self.parameterAsString(parameters, self.FORMULA, context)
expression = QgsExpression(formula)
da = QgsDistanceArea()
da.setSourceCrs(source.sourceCrs())
da.setEllipsoid(context.project().ellipsoid())
expression.setGeomCalculator(da)
expression.setDistanceUnits(context.project().distanceUnits())
expression.setAreaUnits(context.project().areaUnits())
fields = source.fields()
field_index = fields.lookupField(field_name)
if new_field or field_index < 0:
fields.append(QgsField(field_name, field_type, '', width, precision))
(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
fields, source.wkbType(), source.sourceCrs())
exp_context = self.createExpressionContext(parameters, context)
if layer is not None:
exp_context.appendScope(QgsExpressionContextUtils.layerScope(layer))
if not expression.prepare(exp_context):
raise QgsProcessingException(
self.tr('Evaluation error: {0}').format(expression.parserErrorString()))
features = source.getFeatures()
total = 100.0 / source.featureCount() if source.featureCount() else 0
for current, f in enumerate(features):
if feedback.isCanceled():
break
rownum = current + 1
exp_context.setFeature(f)
exp_context.lastScope().setVariable("row_number", rownum)
value = expression.evaluate(exp_context)
if expression.hasEvalError():
feedback.reportError(expression.evalErrorString())
else:
attrs = f.attributes()
if new_field or field_index < 0:
attrs.append(value)
else:
attrs[field_index] = value
f.setAttributes(attrs)
sink.addFeature(f, QgsFeatureSink.FastInsert)
feedback.setProgress(int(current * total))
return {self.OUTPUT: dest_id}
示例9: testCrs
def testCrs(self):
# test setting/getting the source CRS
da = QgsDistanceArea()
# try setting using a CRS object
crs = QgsCoordinateReferenceSystem(3111, QgsCoordinateReferenceSystem.EpsgCrsId)
da.setSourceCrs(crs, QgsProject.instance().transformContext())
self.assertEqual(da.sourceCrs().srsid(), crs.srsid())
示例10: getSemiMajorAndSemiMinorAxis
def getSemiMajorAndSemiMinorAxis(self):
"""Obtains the semi major axis and semi minor axis from the used ellipsoid
"""
currentLayer = self.iface.mapCanvas().currentLayer()
distanceArea = QgsDistanceArea()
distanceArea.setEllipsoid(currentLayer.crs().ellipsoidAcronym())
a = distanceArea.ellipsoidSemiMajor()
b = distanceArea.ellipsoidSemiMinor()
return (a,b)
示例11: simpleMeasure
def simpleMeasure(geom, method=0, ellips=None, crs=None):
# Method defines calculation type:
# 0 - layer CRS
# 1 - project CRS
# 2 - ellipsoidal
if geom.wkbType() in [QGis.WKBPoint, QGis.WKBPoint25D]:
pt = geom.asPoint()
attr1 = pt.x()
attr2 = pt.y()
elif geom.wkbType() in [QGis.WKBMultiPoint, QGis.WKBMultiPoint25D]:
pt = geom.asMultiPoint()
attr1 = pt[0].x()
attr2 = pt[0].y()
else:
measure = QgsDistanceArea()
if method == 2:
measure.setSourceCrs(crs)
measure.setEllipsoid(ellips)
measure.setEllipsoidalMode(True)
attr1 = measure.measure(geom)
if geom.type() == QGis.Polygon:
attr2 = measure.measurePerimeter(geom)
else:
attr2 = None
return (attr1, attr2)
示例12: testMeasureLine
def testMeasureLine(self):
# +-+
# | |
# +-+ +
linestring = QgsGeometry.fromPolyline(
[QgsPoint(0, 0), QgsPoint(1, 0), QgsPoint(1, 1), QgsPoint(2, 1), QgsPoint(2, 0)]
)
da = QgsDistanceArea()
length = da.measure(linestring)
myMessage = "Expected:\n%f\nGot:\n%f\n" % (4, length)
assert length == 4, myMessage
示例13: compute
def compute(self, inPoly, inLns, inField, outPath, progressBar):
polyLayer = ftools_utils.getVectorLayerByName(inPoly)
lineLayer = ftools_utils.getVectorLayerByName(inLns)
polyProvider = polyLayer.dataProvider()
lineProvider = lineLayer.dataProvider()
if polyProvider.crs() != lineProvider.crs():
QMessageBox.warning(self, self.tr("CRS warning!"), self.tr("Warning: Input layers have non-matching CRS.\nThis may cause unexpected results."))
fieldList = ftools_utils.getFieldList(polyLayer)
index = polyProvider.fieldNameIndex(unicode(inField))
if index == -1:
index = polyProvider.fields().count()
fieldList.append(QgsField(unicode(inField), QVariant.Double, "real", 24, 15, self.tr("length field")))
sRs = polyProvider.crs()
inFeat = QgsFeature()
inFeatB = QgsFeature()
outFeat = QgsFeature()
inGeom = QgsGeometry()
outGeom = QgsGeometry()
distArea = QgsDistanceArea()
start = 0.00
add = 100.00 / polyProvider.featureCount()
check = QFile(self.shapefileName)
if check.exists():
if not QgsVectorFileWriter.deleteShapeFile(self.shapefileName):
return
writer = QgsVectorFileWriter(self.shapefileName, self.encoding, fieldList, polyProvider.geometryType(), sRs)
spatialIndex = ftools_utils.createIndex(lineProvider)
polyFit = polyProvider.getFeatures()
while polyFit.nextFeature(inFeat):
inGeom = QgsGeometry(inFeat.geometry())
atMap = inFeat.attributes()
lineList = []
length = 0
lineList = spatialIndex.intersects(inGeom.boundingBox())
if len(lineList) > 0:
check = 0
else:
check = 1
if check == 0:
for i in lineList:
lineProvider.getFeatures(QgsFeatureRequest().setFilterFid(int(i))).nextFeature(inFeatB)
tmpGeom = QgsGeometry(inFeatB.geometry())
if inGeom.intersects(tmpGeom):
outGeom = inGeom.intersection(tmpGeom)
length = length + distArea.measure(outGeom)
outFeat.setGeometry(inGeom)
atMap.append(length)
outFeat.setAttributes(atMap)
writer.addFeature(outFeat)
start = start + 1
progressBar.setValue(start * (add))
del writer
示例14: testMeasureMultiLine
def testMeasureMultiLine(self):
# +-+ +-+-+
# | | | |
# +-+ + + +-+
linestring = QgsGeometry.fromMultiPolyline(
[
[QgsPoint(0, 0), QgsPoint(1, 0), QgsPoint(1, 1), QgsPoint(2, 1), QgsPoint(2, 0)],
[QgsPoint(3, 0), QgsPoint(3, 1), QgsPoint(5, 1), QgsPoint(5, 0), QgsPoint(6, 0)],
]
)
da = QgsDistanceArea()
length = da.measure(linestring)
myMessage = "Expected:\n%f\nGot:\n%f\n" % (9, length)
assert length == 9, myMessage
示例15: _calc_north
def _calc_north(self):
extent = self.canvas.extent()
if self.canvas.layerCount() == 0 or extent.isEmpty():
print "No layers or extent"
return 0
outcrs = self.canvas.mapSettings().destinationCrs()
if outcrs.isValid() and not outcrs.geographicFlag():
crs = QgsCoordinateReferenceSystem()
crs.createFromOgcWmsCrs("EPSG:4326")
transform = QgsCoordinateTransform(outcrs, crs)
p1 = QgsPoint(extent.center())
p2 = QgsPoint(p1.x(), p1.y() + extent.height() * 0.25)
try:
pp1 = transform.transform(p1)
pp2 = transform.transform(p2)
except QgsCsException:
roam.utils.warning("North arrow. Error transforming.")
return None
area = QgsDistanceArea()
area.setEllipsoid(crs.ellipsoidAcronym())
area.setEllipsoidalMode(True)
area.setSourceCrs(crs)
distance, angle, _ = area.computeDistanceBearing(pp1, pp2)
angle = math.degrees(angle)
return angle
else:
return 0