thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-11-18 05:32:52 +00:00
Code Issues Packages Projects Releases Wiki Activity
e83b6d0c2e
ClickHouse/dbms/Functions/GeoHash.cpp
Ivan 97f2a2213e
Move all folders inside /dbms one level up (#9974) 
* Move some code outside dbms/src folder
* Fix paths
2020-04-02 02:51:21 +03:00

345 lines
10 KiB
C++
Raw Blame History

#include <array>
#include <cmath>
#include <cassert>
#include <Functions/GeoHash.h>
namespace DB
{
namespace
{
const char geohash_base32_encode_lookup_table[32] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm',
'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
'y', 'z',
};
// TODO: this could be halved by excluding 128-255 range.
const uint8_t geohash_base32_decode_lookup_table[256] = {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 10, 11, 12, 13, 14, 15, 16, 0xFF, 17, 18, 0xFF, 19, 20, 0xFF,
21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
};
const size_t BITS_PER_SYMBOL = 5;
const size_t MAX_PRECISION = 12;
const size_t MAX_BITS = MAX_PRECISION * BITS_PER_SYMBOL * 1.5;
const Float64 LON_MIN = -180;
const Float64 LON_MAX = 180;
const Float64 LAT_MIN = -90;
const Float64 LAT_MAX = 90;
using Encoded = std::array<uint8_t, MAX_BITS>;
enum CoordType
{
LATITUDE,
LONGITUDE,
};
inline uint8_t singleCoordBitsPrecision(uint8_t precision, CoordType type)
{
// Single coordinate occupies only half of the total bits.
const uint8_t bits = (precision * BITS_PER_SYMBOL) / 2;
if (precision & 0x1 && type == LONGITUDE)
{
return bits + 1;
}
return bits;
}
inline Encoded encodeCoordinate(Float64 coord, Float64 min, Float64 max, uint8_t bits)
{
Encoded result;
result.fill(0);
for (size_t i = 0; i < bits; ++i)
{
const Float64 mid = (max + min) / 2;
if (coord >= mid)
{
result[i] = 1;
min = mid;
}
else
{
result[i] = 0;
max = mid;
}
}
return result;
}
inline Float64 decodeCoordinate(const Encoded & coord, Float64 min, Float64 max, uint8_t bits)
{
Float64 mid = (max + min) / 2;
for (size_t i = 0; i < bits; ++i)
{
const auto c = coord[i];
if (c == 1)
{
min = mid;
}
else
{
max = mid;
}
mid = (max + min) / 2;
}
return mid;
}
inline Encoded merge(const Encoded & encodedLon, const Encoded & encodedLat, uint8_t precision)
{
Encoded result;
result.fill(0);
const auto bits = (precision * BITS_PER_SYMBOL) / 2;
uint8_t i = 0;
for (; i < bits; ++i)
{
result[i * 2 + 0] = encodedLon[i];
result[i * 2 + 1] = encodedLat[i];
}
// in case of even precision, add last bit of longitude
if (precision & 0x1)
{
result[i * 2] = encodedLon[i];
}
return result;
}
inline std::tuple<Encoded, Encoded> split(const Encoded & combined, uint8_t precision)
{
Encoded lat, lon;
lat.fill(0);
lon.fill(0);
size_t i = 0;
for (; i < precision * BITS_PER_SYMBOL - 1; i += 2)
{
// longitude is even bits
lon[i / 2] = combined[i];
lat[i / 2] = combined[i + 1];
}
// precision is even, read the last bit as lat.
if (precision & 0x1)
{
lon[i / 2] = combined[precision * BITS_PER_SYMBOL - 1];
}
return std::tie(lon, lat);
}
inline void base32Encode(const Encoded & binary, uint8_t precision, char * out)
{
extern const char geohash_base32_encode_lookup_table[32];
for (size_t i = 0; i < precision * BITS_PER_SYMBOL; i += BITS_PER_SYMBOL)
{
uint8_t v = binary[i];
v <<= 1;
v |= binary[i + 1];
v <<= 1;
v |= binary[i + 2];
v <<= 1;
v |= binary[i + 3];
v <<= 1;
v |= binary[i + 4];
assert(v < 32);
*out = geohash_base32_encode_lookup_table[v];
++out;
}
}
inline Encoded base32Decode(const char * encoded_string, size_t encoded_length)
{
extern const uint8_t geohash_base32_decode_lookup_table[256];
Encoded result;
for (size_t i = 0; i < encoded_length; ++i)
{
const uint8_t c = static_cast<uint8_t>(encoded_string[i]);
const uint8_t decoded = geohash_base32_decode_lookup_table[c] & 0x1F;
result[i * 5 + 4] = (decoded >> 0) & 0x01;
result[i * 5 + 3] = (decoded >> 1) & 0x01;
result[i * 5 + 2] = (decoded >> 2) & 0x01;
result[i * 5 + 1] = (decoded >> 3) & 0x01;
result[i * 5 + 0] = (decoded >> 4) & 0x01;
}
return result;
}
inline Float64 getMaxSpan(CoordType type)
{
if (type == LONGITUDE)
{
return LON_MAX - LON_MIN;
}
return LAT_MAX - LAT_MIN;
}
inline Float64 getSpan(uint8_t precision, CoordType type)
{
const auto bits = singleCoordBitsPrecision(precision, type);
// since every bit of precision divides span by 2, divide max span by 2^bits.
return ldexp(getMaxSpan(type), -1 * bits);
}
inline uint8_t geohashPrecision(uint8_t precision)
{
if (precision == 0 || precision > MAX_PRECISION)
{
precision = MAX_PRECISION;
}
return precision;
}
inline size_t geohashEncodeImpl(Float64 longitude, Float64 latitude, uint8_t precision, char * out)
{
const Encoded combined = merge(
encodeCoordinate(longitude, LON_MIN, LON_MAX, singleCoordBitsPrecision(precision, LONGITUDE)),
encodeCoordinate(latitude, LAT_MIN, LAT_MAX, singleCoordBitsPrecision(precision, LATITUDE)),
precision);
base32Encode(combined, precision, out);
return precision;
}
}
size_t geohashEncode(Float64 longitude, Float64 latitude, uint8_t precision, char * out)
{
precision = geohashPrecision(precision);
return geohashEncodeImpl(longitude, latitude, precision, out);
}
void geohashDecode(const char * encoded_string, size_t encoded_len, Float64 * longitude, Float64 * latitude)
{
const uint8_t precision = std::min(encoded_len, static_cast<size_t>(MAX_PRECISION));
if (precision == 0)
{
// Empty string is converted to (0, 0)
*longitude = 0;
*latitude = 0;
return;
}
Encoded lat_encoded, lon_encoded;
std::tie(lon_encoded, lat_encoded) = split(base32Decode(encoded_string, precision), precision);
*longitude = decodeCoordinate(lon_encoded, LON_MIN, LON_MAX, singleCoordBitsPrecision(precision, LONGITUDE));
*latitude = decodeCoordinate(lat_encoded, LAT_MIN, LAT_MAX, singleCoordBitsPrecision(precision, LATITUDE));
}
GeohashesInBoxPreparedArgs geohashesInBoxPrepare(const Float64 longitude_min,
const Float64 latitude_min,
const Float64 longitude_max,
const Float64 latitude_max,
uint8_t precision)
{
precision = geohashPrecision(precision);
if (longitude_max < longitude_min || latitude_max < latitude_min)
{
return {};
}
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.
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)));
return GeohashesInBoxPreparedArgs{
items_count,
precision,
lon_min,
lat_min,
lon_max,
lat_max,
lon_step,
lat_step
};
}
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)
{
return 0;
}
UInt64 items = 0;
for (auto lon = args.longitude_min; lon < args.longitude_max; lon += args.longitude_step) // NOLINT
{
for (auto lat = args.latitude_min; lat < args.latitude_max; lat += args.latitude_step) // NOLINT
{
assert(items <= args.items_count);
size_t l = geohashEncodeImpl(lon, lat, args.precision, out);
out += l;
*out = '\0';
++out;
++items;
}
}
if (items == 0)
{
size_t l = geohashEncodeImpl(args.longitude_min, args.latitude_min, args.precision, out);
out += l;
*out = '\0';
++out;
++items;
}
return items;
}
}
Reference in New Issue View Git Blame Copy Permalink