Analytics Toolbox for BigQuery

Analytics Toolbox for BigQuery

constructors

This module contains functions that create new geographies from coordinates or already existing geographies.

ST_BEZIERSPLINE

Description

Takes a line and returns a curved version of it by applying a Bezier spline algorithm. Note that the resulting geography will be a LineString with additional points inserted.

  • geog: GEOGRAPHY input LineString.
  • resolution: INT64|NULL total time in milliseconds assigned to the line. If NULL the default value 10000 is used. Internal curve vertices are generated in 10 ms increments, so the maximum number of resulting points will be resolution/10 (close points may be merged resulting in less points). A higher number will increase the accuracy of the result but will increase the computation time and number of points.
  • sharpness: FLOAT64|NULL a measure of how curvy the path should be between splines. If NULL the default value 0.85 is used.

Example

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SELECT `carto-os`.carto.ST_BEZIERSPLINE(
  ST_GEOGFROMTEXT(
    "LINESTRING (-76.091308 18.427501,-76.695556 18.729501,-76.552734 19.40443,-74.61914 19.134789,-73.652343 20.07657,-73.157958 20.210656)"
  ),
  10000,
  0.9
);
-- LINESTRING(-76.091308 18.427501, -76.0916216712943 ...

ST_MAKEELLIPSE

Description

Takes a Point and calculates the ellipse polygon given two semi-axes expressed in variable units and steps for precision.

  • center: GEOGRAPHY center point.
  • xSemiAxis: FLOAT64 semi (major) axis of the ellipse along the x-axis.
  • ySemiAxis: FLOAT64 semi (minor) axis of the ellipse along the y-axis.
  • angle: FLOAT64|NULL angle of rotation (along the vertical axis), from North in decimal degrees, negative clockwise. If NULL the default value 0 is used.
  • units: STRING|NULL units of length, the supported options are: miles, kilometers, and degrees. If NULLthe default value kilometers is used.
  • steps: INT64|NULL number of steps. If NULL the default value 64 is used.

Example

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SELECT `carto-os`.carto.ST_MAKEELLIPSE(
  ST_GEOGPOINT(-73.9385,40.6643),
  5,
  3,
  -30,
  "miles",
  80
);
-- POLYGON((-73.8558575786687 40.7004828957859 ...

ST_MAKEENVELOPE

Description Creates a rectangular Polygon from the minimum and maximum values for X and Y.

  • xmin: FLOAT64 minimum value for X.
  • ymin: FLOAT64 minimum value for Y.
  • xmax: FLOAT64 maximum value for X.
  • ymax: FLOAT64 maximum value for Y.

Return type

GEOGRAPHY

Example

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SELECT `carto-os`.carto.ST_MAKEENVELOPE(0,0,1,1);
-- POLYGON((1 0, 1 1, 0 1, 0 0, 1 0))

ST_TILEENVELOPE

Description Returns the boundary polygon of a tile given its zoom level and its X and Y indices.

  • zoomLevel: INT64 zoom level of the tile.
  • xTile: INT64 X index of the tile.
  • yTile: INT64 Y index of the tile.

Return type

GEOGRAPHY

Example

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SELECT `carto-os`.carto.ST_TILEENVELOPE(10,384,368);
-- POLYGON((-45 45.089035564831, -45 44.840290651398, -44.82421875 44.840290651398, -44.6484375 44.840290651398, -44.6484375 45.089035564831, -44.82421875 45.089035564831, -45 45.089035564831))
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This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 960401.