How do I filter large set of points (481,308) in QGIS attribute table by fixing the extents(Lat Long values)

Question

I have a large set of points (481,308) in single QGIS layer with the attribute table(ID, LAT, LONG,..ETC). But I only need points which fall inside particular area or polygon, I have fixed the extents of the polygon, as shown below:

1)North of Point1 12.978649° 77 .603701°

2)East of point1 12.952451° 77.633003°

3)East of point2 12.930359° 77.647210°

4)South of point2 12.893661° 77.636665°

5)West of point2 12.906764° 77.597081°

6)West of point1 12.952262° 77.577471°

What expression should I use to filter out points which come inside my polygon area?

Answer 1

Assuming coordinates are Lat/Long, an example layer from Random points in extent:

Use Select by expression with intersects() function between point's geometry and desired polygon:

intersects( $geometry, geom_from_wkt( 'POLYGON((77.603701 12.978649, 77.633003 12.952451, 77.647210 12.930359, 77.636665 12.893661, 77.597081 12.90676, 77.577471 12.952262, 77.603701 12.978649))' ))

Don't forget to close the polygon

The result:

---

Step by step procedure for this reproducible example:

Answer 2

You could create a polygon with your extent (I dont really understand how you define the polygon extent, the number of point is unclear...) then use the select by location fonction (in the vector menu or in the processing toolbox) to select your point.

Depending if you need to reuse the selection polygon you could create it in a temporary layer or in a more durable format.

You could also use the select by expression button with this expression (replace the X and Y by the vertices coordinate of your extent polygon)

within(  $geometry ,geom_from_wkt( 'POLYGON ((X1 Y1, X2 Y2, ... ...,Xn Yn ))'))

EDIT: if you want to filter your data you could try to adapt the previous expression to SQL in the query builder (I tried, but can't get it to work...)