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XQuery cts:element-child-geospatial-query

MarkLogic 10 Product Documentation
cts.elementChildGeospatialQuery

cts.elementChildGeospatialQuery(
   parent-element-name as xs.QName[],
   child-element-names as xs.QName[],
   regions as cts.region[],
   [options as String[]],
   [weight as Number?]
) as cts.elementChildGeospatialQuery

Summary

Returns a query matching elements by name which has specific element children representing latitude and longitude values for a point contained within the given geographic box, circle, or polygon, or equal to the given point. Points that lie between the southern boundary and the northern boundary of a box, travelling northwards, and between the western boundary and the eastern boundary of the box, travelling eastwards, will match. Points contained within the given radius of the center point of a circle will match, using the curved distance on the surface of the Earth. Points contained within the given polygon will match, using great circle arcs over a spherical model of the Earth as edges. An error may result if the polygon is malformed in some way. Points equal to the a given point will match, taking into account the fact that longitudes converge at the poles. Using the geospatial query constructors requires a valid geospatial license key; without a valid license key, searches that include geospatial queries will throw an exception.

Parameters
parent-element-name One or more parent element QNames to match. When multiple QNames are specified, the query matches if any QName matches.
child-element-names One or more child element QNames to match. When multiple QNames are specified, the query matches if any QName matches; however, only the first matching latitude child in any point instance will be checked. The element must specify both latitude and longitude coordinates.
regions One or more geographic boxes, circles, polygons, or points. Where multiple regions are specified, the query matches if any region matches.
options Options to this query. The default is ().

Options include:

"coordinate-system=string"
Use the given coordinate system. Valid values are:
wgs84
The WGS84 coordinate system.
wgs84/double
The WGS84 coordinate system at double precision.
etrs89
The ETRS89 coordinate system.
etrs89/double
The ETRS89 coordinate system at double precision.
raw
The raw (unmapped) coordinate system.
raw/double
The raw coordinate system at double precision.
"precision=string"
Use the coordinate system at the given precision. Allowed values: float (default) and double.
"units=value"
Measure distance and the radii of circles in the specified units. Allowed values: miles (default), km, feet, meters.
"boundaries-included"
Points on boxes', circles', and polygons' boundaries are counted as matching. This is the default.
"boundaries-excluded"
Points on boxes', circles', and polygons' boundaries are not counted as matching.
"boundaries-latitude-excluded"
Points on boxes' latitude boundaries are not counted as matching.
"boundaries-longitude-excluded"
Points on boxes' longitude boundaries are not counted as matching.
"boundaries-south-excluded"
Points on the boxes' southern boundaries are not counted as matching.
"boundaries-west-excluded"
Points on the boxes' western boundaries are not counted as matching.
"boundaries-north-excluded"
Points on the boxes' northern boundaries are not counted as matching.
"boundaries-east-excluded"
Points on the boxes' eastern boundaries are not counted as matching.
"boundaries-circle-excluded"
Points on circles' boundary are not counted as matching.
"boundaries-endpoints-excluded"
Points on linestrings' boundary (the endpoints) are not counted as matching.
"cached"
Cache the results of this query in the list cache.
"uncached"
Do not cache the results of this query in the list cache.
"type=long-lat-point"
Specifies the format for the point in the data as longitude first, latitude second.
"type=point"
Specifies the format for the point in the data as latitude first, longitude second. This is the default format.
"score-function=function"
Use the selected scoring function. The score function may be:
linear
Use a linear function of the difference between the specified query value and the matching value in the index to calculate a score for this range query.
reciprocal
Use a reciprocal function of the difference between the specified query value and the matching value in the index to calculate a score for this range query.
zero
This range query does not contribute to the score. This is the default.
"slope-factor=number"
Apply the given number as a scaling factor to the slope of the scoring function. The default is 1.0.
"synonym"
Specifies that all of the terms in the $regions parameter are considered synonyms for scoring purposes. The result is that occurrences of more than one of the synonyms are scored as if there are more occurrence of the same term (as opposed to having a separate term that contributes to score).
weight A weight for this query. The default is 1.0.

Usage Notes

The point value is expressed in the content of the element as a child of numbers, separated by whitespace and punctuation (excluding decimal points and sign characters).

The value of the precision option takes precedence over that implied by the governing coordinate system name, including the value of the coordinate-system option. For example, if the governing coordinate system is "wgs84/double" and the precision option is "float", then the query uses single precision.

Point values and boundary specifications of boxes are given in degrees relative to the WGS84 coordinate system. Southern latitudes and Western longitudes take negative values. Longitudes will be wrapped to the range (-180,+180) and latitudes will be clipped to the range (-90,+90).

If the northern boundary of a box is south of the southern boundary, no points will match. However, longitudes wrap around the globe, so that if the western boundary is east of the eastern boundary, then the box crosses the anti-meridian.

Special handling occurs at the poles, as all longitudes exist at latitudes +90 and -90.

If neither "cached" nor "uncached" is present, it specifies "cached".

"score-function=linear" means that values that are further away from the bounds will score higher. "score-function=reciprocal" means that values that are closer to the bounds will score higher. The functions are scaled appropriately for different types, so that in general the default slope factor will provide useful results. Using a slope factor greater than 1 gives distinct scores over a smaller range of values, and produces generally higher scores. Using a slope factor less than 1 gives distinct scores over a wider range of values, and produces generally lower scores.

See Also

Example

// create a document with test data
declareUpdate();
xdmp.documentInsert("/point01.xml", xdmp.unquote(
 ' <item><point><pos>10.5, 30.0</pos></point></item>' )),

xdmp.documentInsert("/point02.xml", xdmp.unquote(
 '  <item><point><pos>15.35, 35.34</pos></point></item>' )),

xdmp.documentInsert("/point03.xml", xdmp.unquote(
 '  <item><point><pos>5.11, 40.55</pos></point></item>' ));

// ******
// Now the following search:

cts.search(cts.elementChildGeospatialQuery(xs.QName("point"),
          xs.QName("pos"),
                  cts.box(10.0, 35.0, 20.0, 40.0)));

// => The /point02.xml document (because
//    <point>15.35, 35.34</point> matches).

// ******
// And the following search:

cts.search(cts.elementChildGeospatialQuery(xs.QName("point"),
          xs.QName("pos"),
                  cts.box(10.0, 40.0, 20.0, 35.0)));

// => The /point01.xml document(wrapping around the Earth):

// ******
// And the following search:

cts.search(cts.elementChildGeospatialQuery(xs.QName("point"),
          xs.QName("pos"),
                  cts.box(20.0, 35.0, 10.0, 40.0)));

// => throws an XDMP-BADBOX error (because latitudes do not wrap)

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