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Avoid floating point error in geohashesInBox #11369

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This commit is contained in:
Alexey Milovidov 2020-06-28 02:07:24 +03:00
parent b4695846df
commit c35841e4e1
4 changed files with 48 additions and 37 deletions
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75
src/Functions/GeoHash.cpp
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@ -260,15 +260,21 @@ void geohashDecode(const char * encoded_string, size_t encoded_len, Float64 * lo
*latitude = decodeCoordinate(lat_encoded, LAT_MIN, LAT_MAX, singleCoordBitsPrecision(precision, LATITUDE));
}
GeohashesInBoxPreparedArgs geohashesInBoxPrepare(Float64 longitude_min,
Float64 latitude_min,
Float64 longitude_max,
Float64 latitude_max,
uint8_t precision)
GeohashesInBoxPreparedArgs geohashesInBoxPrepare(
Float64 longitude_min,
Float64 latitude_min,
Float64 longitude_max,
Float64 latitude_max,
uint8_t precision)
{
precision = geohashPrecision(precision);
if (longitude_max < longitude_min || latitude_max < latitude_min)
if (longitude_max < longitude_min
|| latitude_max < latitude_min
|| isnan(longitude_min)
|| isnan(longitude_max)
|| isnan(latitude_min)
|| isnan(latitude_max))
{
return {};
}
@ -281,51 +287,52 @@ GeohashesInBoxPreparedArgs geohashesInBoxPrepare(Float64 longitude_min,
const auto lon_step = getSpan(precision, LONGITUDE);
const auto lat_step = getSpan(precision, LATITUDE);
// align max to the right(or up) border of geohash grid cell to ensure that cell is in result.
/// Align max to the right (or up) border of geohash grid cell to ensure that cell is in result.
Float64 lon_min = floor(longitude_min / lon_step) * lon_step;
Float64 lat_min = floor(latitude_min / lat_step) * lat_step;
Float64 lon_max = ceil(longitude_max / lon_step) * lon_step;
Float64 lat_max = ceil(latitude_max / lat_step) * lat_step;
const auto lon_span = lon_max - lon_min;
const auto lat_span = lat_max - lat_min;
// in case of a very small (or zero) span, produce at least 1 item.
const auto items_count = std::max(size_t{1}, static_cast<size_t>(ceil(lon_span/lon_step * lat_span/lat_step)));
UInt32 lon_items = (lon_max - lon_min) / lon_step;
UInt32 lat_items = (lat_max - lat_min) / lat_step;
return GeohashesInBoxPreparedArgs{
items_count,
precision,
lon_min,
lat_min,
lon_max,
lat_max,
lon_step,
lat_step
return GeohashesInBoxPreparedArgs
{
UInt64(lon_items) * lat_items,
lon_items,
lat_items,
lon_min,
lat_min,
lon_step,
lat_step,
precision
};
}
UInt64 geohashesInBox(const GeohashesInBoxPreparedArgs & args, char * out)
{
if (args.items_count == 0
|| args.precision == 0
|| args.precision > MAX_PRECISION
|| args.latitude_min > args.latitude_max
|| args.longitude_min > args.longitude_max
|| args.longitude_step <= 0
|| args.latitude_step <= 0)
if (args.longitude_items == 0
|| args.latitude_items == 0
|| args.precision == 0
|| args.precision > MAX_PRECISION
|| args.longitude_step <= 0
|| args.latitude_step <= 0)
{
return 0;
}
UInt64 items = 0;
for (auto lon = args.longitude_min; lon < args.longitude_max; lon += args.longitude_step) // NOLINT
for (size_t i = 0; i < args.longitude_items; ++i)
{
for (auto lat = args.latitude_min; lat < args.latitude_max; lat += args.latitude_step) // NOLINT
for (size_t j = 0; j < args.latitude_items; ++j)
{
assert(items <= args.items_count);
size_t length = geohashEncodeImpl(
args.longitude_min + args.longitude_step * i,
args.latitude_min + args.latitude_step * j,
args.precision,
out);
size_t l = geohashEncodeImpl(lon, lat, args.precision, out);
out += l;
out += length;
*out = '\0';
++out;
@ -335,8 +342,8 @@ UInt64 geohashesInBox(const GeohashesInBoxPreparedArgs & args, char * out)
if (items == 0)
{
size_t l = geohashEncodeImpl(args.longitude_min, args.latitude_min, args.precision, out);
out += l;
size_t length = geohashEncodeImpl(args.longitude_min, args.latitude_min, args.precision, out);
out += length;
*out = '\0';
++out;

8
src/Functions/GeoHash.h
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@ -23,15 +23,17 @@ std::vector<std::pair<Float64, Float64>> geohashCoverBox(
struct GeohashesInBoxPreparedArgs
{
UInt64 items_count = 0;
uint8_t precision = 0;
UInt32 longitude_items = 0;
UInt32 latitude_items = 0;
Float64 longitude_min = 0.0;
Float64 latitude_min = 0.0;
Float64 longitude_max = 0.0;
Float64 latitude_max = 0.0;
Float64 longitude_step = 0.0;
Float64 latitude_step = 0.0;
uint8_t precision = 0;
};
GeohashesInBoxPreparedArgs geohashesInBoxPrepare(

1
tests/queries/0_stateless/01351_geohash_assert.reference Normal file
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@ -0,0 +1 @@
['7zz','ebp','ebr','ebx','ebz','ecp','ecr','ecx','ecz','efp','efr','efx','efz','egp','egr','egx','egz','eup','eur','eux','euz','evp','evr','evx','evz','eyp','eyr','eyx','eyz','ezp','ezr','ezx','ezz','gbp','gbr','gbx','gbz','gcp','gcr','gcx','gcz','gfp','gfr','gfx','gfz','ggp','ggr','ggx','ggz','gup','gur','gux','guz','gvp','gvr','gvx','gvz','gyp','gyr','gyx','gyz','gzp','gzr','gzx','gzz','kpb','s00','s02','s08','s0b','s10','s12','s18','s1b','s40','s42','s48','s4b','s50','s52','s58','s5b','sh0','sh2','sh8','shb','sj0','sj2','sj8','sjb','sn0','sn2','sn8','snb','sp0','sp2','sp8','spb','u00','u02','u08','u0b','u10','u12','u18','u1b','u40','u42','u48','u4b','u50','u52','u58','u5b','uh0','uh2','uh8','uhb','uj0','uj2','uj8','ujb','un0','un2','un8','unb','up0','up2','up8','upb']

1
tests/queries/0_stateless/01351_geohash_assert.sql Normal file
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@ -0,0 +1 @@
SELECT arraySort(geohashesInBox(-1., -1., 1., inf, 3));