contains

Returns true if geometry b lies in geometry a and their interiors intersect.

Geometry a contains geometry b if all points of b are in the interior or at the boundary of a and the interiors of a and b have at least one point in common.

note

According to the definition above, a geometry does not contain its boundary, so for example, a LineString that is completely contained in the boundary of a Polygon is not considered to be contained in that Polygon.

In most cases covers should be used, as it has a simpler definition and allows for additional optimizations.

contains is the converse of within: contains(a, b) === within(b, a).

warning

Do not use this function with invalid geometries. You will get unexpected results.

Parameters

Name	Type	Description
a	Geometry | Prepared<Geometry>	First geometry
b	Geometry	Second geometry

Returns

boolean

true if geometry a contains geometry b

Throws

• GEOSError on unsupported geometry types (curved)

See also

• within converse of contains
• covers more inclusive contains
• containsProperly less inclusive contains
• prepare improves performance of repeated calls against a single geometry

Examples

contains: true

const a = lineString([ [ 0, 13 ], [ 4, 15 ], [ 2, 10 ] ]);
const b = multiPoint([ [ 2, 10 ], [ 4, 15 ] ]);
const ab_contain = contains(a, b); // true

const c = polygon([ [ [ 10, 13 ], [ 14, 15 ], [ 15, 10 ], [ 10, 13 ] ] ]);
const d = multiPoint([ [ 12, 14 ], [ 13, 14 ] ]);
const cd_contain = contains(c, d); // true

const e = polygon([ [ [ 0, 0 ], [ 0, 5 ], [ 5, 5 ], [ 5, 0 ], [ 0, 0 ] ] ]);
const f = lineString([ [ 0, 5 ], [ 5, 5 ], [ 0, 0 ] ]);
const ef_contain = contains(e, f); // true

const g = polygon([ [ [ 10, 0 ], [ 10, 5 ], [ 15, 5 ], [ 15, 0 ], [ 10, 0 ] ] ]);
const h = polygon([ [ [ 11, 2 ], [ 14, 5 ], [ 15, 1 ], [ 11, 2 ] ] ]);
const gh_contain = contains(g, h); // true

const a = lineString([ [ 0, 13 ], [ 4, 15 ], [ 2, 10 ] ]); const b = multiPoint([ [ 2, 10 ], [ 4, 15 ] ]); const ab_contain = contains(a, b); // true const c = polygon([ [ [ 10, 13 ], [ 14, 15 ], [ 15, 10 ], [ 10, 13 ] ] ]); const d = multiPoint([ [ 12, 14 ], [ 13, 14 ] ]); const cd_contain = contains(c, d); // true const e = polygon([ [ [ 0, 0 ], [ 0, 5 ], [ 5, 5 ], [ 5, 0 ], [ 0, 0 ] ] ]); const f = lineString([ [ 0, 5 ], [ 5, 5 ], [ 0, 0 ] ]); const ef_contain = contains(e, f); // true const g = polygon([ [ [ 10, 0 ], [ 10, 5 ], [ 15, 5 ], [ 15, 0 ], [ 10, 0 ] ] ]); const h = polygon([ [ [ 11, 2 ], [ 14, 5 ], [ 15, 1 ], [ 11, 2 ] ] ]); const gh_contain = contains(g, h); // true

contains: false

const a = lineString([ [ 0, 13 ], [ 4, 15 ], [ 2, 10 ] ]);
const b = point([ 2, 10 ]);
const ab_contain = contains(a, b); // false - no interior point in common

const c = polygon([ [ [ 10, 13 ], [ 14, 15 ], [ 15, 10 ], [ 10, 13 ] ] ]);
const d = lineString([ [ 10, 13 ], [ 14, 15 ], [ 15, 10 ] ]);
const cd_contain = contains(c, d); // false - no interior point in common

const e = polygon([
    [ [ 0, 0 ], [ 0, 5 ], [ 5, 5 ], [ 5, 0 ], [ 0, 0 ] ],
    [ [ 2, 2 ], [ 2, 4 ], [ 4, 4 ], [ 4, 2 ], [ 2, 2 ] ],
]);
const f = multiPoint([ [ 1, 1 ], [ 3, 3 ] ]);
const ef_contain = contains(e, f); // false

const g = polygon([ [ [ 10, 0 ], [ 10, 5 ], [ 15, 5 ], [ 15, 0 ], [ 10, 0 ] ] ]);
const h = lineString([ [ 12, 1 ], [ 16, 1 ] ]);
const gh_contain = contains(g, h); // false

const a = lineString([ [ 0, 13 ], [ 4, 15 ], [ 2, 10 ] ]); const b = point([ 2, 10 ]); const ab_contain = contains(a, b); // false - no interior point in common const c = polygon([ [ [ 10, 13 ], [ 14, 15 ], [ 15, 10 ], [ 10, 13 ] ] ]); const d = lineString([ [ 10, 13 ], [ 14, 15 ], [ 15, 10 ] ]); const cd_contain = contains(c, d); // false - no interior point in common const e = polygon([ [ [ 0, 0 ], [ 0, 5 ], [ 5, 5 ], [ 5, 0 ], [ 0, 0 ] ], [ [ 2, 2 ], [ 2, 4 ], [ 4, 4 ], [ 4, 2 ], [ 2, 2 ] ], ]); const f = multiPoint([ [ 1, 1 ], [ 3, 3 ] ]); const ef_contain = contains(e, f); // false const g = polygon([ [ [ 10, 0 ], [ 10, 5 ], [ 15, 5 ], [ 15, 0 ], [ 10, 0 ] ] ]); const h = lineString([ [ 12, 1 ], [ 16, 1 ] ]); const gh_contain = contains(g, h); // false