Re: [sqlite] geopoly_contains_point(P,X,Y) doc is overly modest
oh, I hope you dont do that since the application I am working on hopes to exploit the retval = 4 of geopoly_overlap ! regards, Graham On 02-12-2018 7:52 am, Richard Hipp wrote: On 12/1/18, Larry Brasfield wrote: The documentation at https://www.sqlite.org/geopoly.html , at 3.8. for geopoly_contains_point(), asserts that the function “returns true if and only if the coordinate X,Y is inside or on the boundary of the polygon P.” As now implemented, in the v3.26 release, it returns 1 where the point is on a boundary and 2 where the point is inside of the boundary. The geopoly_overlap() and geopoly_within() routines are similarly modest about what they compute. Geopoly_within(A,B) returns +1 if B is completely contained inside of A, and returns +2 if A and B are the same polygon. Geopoly_overlap(A,B) returns 4 different non-zero values (1, 2, 3, and 4) depending on whether or not A is contained in B (2), B is contained in A (3), A and B are the same polygon (4), or if they just overlap (1). I haven't documented those behaviors, because I wanted to leave myself some wiggle room in case I need to change the behavior in the future. ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] geopoly_contains_point(P,X,Y) doc is overly modest
On 12/1/18, Keith Medcalf wrote: > >>Maybe it should say 'Non-Zero' or 'Greater than Zero' rather than >>true, since true, as a symbol, as a special value. > > Yes and no, True and False is SQLite work as one would expect (assuming that > one is a programmer is a language that behaves as the underlying hardware > (CPU) behaves). Yeah, but Mr. Damon is probably right that the documentation should be more precise. So I have now updated it. -- D. Richard Hipp d...@sqlite.org ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] geopoly_contains_point(P,X,Y) doc is overly modest
>Maybe it should say 'Non-Zero' or 'Greater than Zero' rather than >true, since true, as a symbol, as a special value. Yes and no, True and False is SQLite work as one would expect (assuming that one is a programmer is a language that behaves as the underlying hardware (CPU) behaves). The "False" state is any state in which all the bits are zero. The "True" state is one in which ANY bit is non-zero. Therefore you get: sqlite> select -1 is true; 1 sqlite> select 0 is true; 0 sqlite> select 1 is true; 1 sqlite> select 2 is true; 1 and conversely for "is false". You can also treat True and False as "values" in which case True has the arbitrary integer value 1, and false has the arbitrary integer value 0 (which complies with the "True means ANY bit is 1 and false means NO bits are one". Any arbitrary non-zero value could have been chosen for the "value" of True when it is used as a value. Using the expression "= TRUE" and "= FALSE" is likely a programmer error, just as "= NULL" is likely a programmer error, because what is really meant is "is TRUE", "is FALSE" and "is NULL" ... --- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] geopoly_contains_point(P,X,Y) doc is overly modest
On 12/1/18 1:52 PM, Richard Hipp wrote: > On 12/1/18, Larry Brasfield wrote: >> The documentation at https://www.sqlite.org/geopoly.html , at 3.8. for >> geopoly_contains_point(), asserts that the function “returns true if and >> only if the coordinate X,Y is inside or on the boundary of the polygon P.” >> As now implemented, in the v3.26 release, it returns 1 where the point is on >> a boundary and 2 where the point is inside of the boundary. > The geopoly_overlap() and geopoly_within() routines are similarly > modest about what they compute. Geopoly_within(A,B) returns +1 if B > is completely contained inside of A, and returns +2 if A and B are the > same polygon. Geopoly_overlap(A,B) returns 4 different non-zero > values (1, 2, 3, and 4) depending on whether or not A is contained in > B (2), B is contained in A (3), A and B are the same polygon (4), or > if they just overlap (1). > > I haven't documented those behaviors, because I wanted to leave myself > some wiggle room in case I need to change the behavior in the future. Maybe it should say 'Non-Zero' or 'Greater than Zero' rather than true, since true, as a symbol, as a special value. -- Richard Damon ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] geopoly_contains_point(P,X,Y) doc is overly modest
On 12/1/18, Larry Brasfield wrote: > The documentation at https://www.sqlite.org/geopoly.html , at 3.8. for > geopoly_contains_point(), asserts that the function “returns true if and > only if the coordinate X,Y is inside or on the boundary of the polygon P.” > As now implemented, in the v3.26 release, it returns 1 where the point is on > a boundary and 2 where the point is inside of the boundary. The geopoly_overlap() and geopoly_within() routines are similarly modest about what they compute. Geopoly_within(A,B) returns +1 if B is completely contained inside of A, and returns +2 if A and B are the same polygon. Geopoly_overlap(A,B) returns 4 different non-zero values (1, 2, 3, and 4) depending on whether or not A is contained in B (2), B is contained in A (3), A and B are the same polygon (4), or if they just overlap (1). I haven't documented those behaviors, because I wanted to leave myself some wiggle room in case I need to change the behavior in the future. -- D. Richard Hipp d...@sqlite.org ___ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
