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Fix a bug in file geohash/geohash.c

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Add missing bit shifts in the function geohashstr_to_interleaved in order to be able to calculate correctly the  
    1) geo coordinates from a given geohash and 
    2) neigbor geohashes of a given geohash.

The incorrect calculation of neighbor geohashes e.g. has the following impact on the deduplication with lieu: Features are compared that should not be compared because they are too far away from each other. This often results in distances between duplicates that exceed by far the max. expected distance according to the used geohash precision.
This commit is contained in:
in-cloud-opensource
2019-12-12 11:34:39 +01:00
committed by GitHub
parent 95bf70eb35
commit ed41f42c97
1 changed files with 17 additions and 5 deletions
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22
src/geohash/geohash.c
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@@ -292,16 +292,28 @@ static int geohashstr_to_interleaved(char *r, size_t length, uint16_t *interleav
if(j== 0) i[0] = map[c[ 0]]<<11; if(j== 0) i[0] = map[c[ 0]]<<11;
if(j== 1) i[0] += map[c[ 1]]<< 6; if(j== 1) i[0] += map[c[ 1]]<< 6;
if(j== 2) i[0] += map[c[ 2]]<< 1; if(j== 2) i[0] += map[c[ 2]]<< 1;
if(j== 3) i[0] += map[c[ 3]]>> 4; if(j== 3) {
i[0] += map[c[ 3]]>> 4;
i[1] = map[c[ 3]]<<12;
}
if(j== 4) i[1] += map[c[ 4]]<< 7; if(j== 4) i[1] += map[c[ 4]]<< 7;
if(j== 5) i[1] += map[c[ 5]]<< 2; if(j== 5) i[1] += map[c[ 5]]<< 2;
if(j== 6) i[1] += map[c[ 6]]>> 3; if(j== 6) {
i[1] += map[c[ 6]]>> 3;
i[2] = map[c[ 6]]<<13;
}
if(j== 7) i[2] += map[c[ 7]]<< 8; if(j== 7) i[2] += map[c[ 7]]<< 8;
if(j== 8) i[2] += map[c[ 8]]<< 3; if(j== 8) i[2] += map[c[ 8]]<< 3;
if(j== 9) i[2] += map[c[ 9]]>> 2; if(j== 9) {
i[2] += map[c[ 9]]>> 2;
i[3] = map[c[ 9]]<<14;
}
if(j==10) i[3] += map[c[10]]<< 9; if(j==10) i[3] += map[c[10]]<< 9;
if(j==11) i[3] += map[c[11]]<< 4; if(j==11) i[3] += map[c[11]]<< 4;
if(j==12) i[3] += map[c[12]]>> 1; if(j==12) {
i[3] += map[c[12]]>> 1;
i[4] = map[c[12]]<<15;
}
if(j==13) i[4] += map[c[13]]<<10; if(j==13) i[4] += map[c[13]]<<10;
if(j==14) i[4] += map[c[14]]<< 5; if(j==14) i[4] += map[c[14]]<< 5;
if(j==15) i[4] += map[c[15]]>> 0; if(j==15) i[4] += map[c[15]]>> 0;
@@ -514,4 +526,4 @@ int geohash_neighbors(char *hashcode, char *dst, size_t dst_length, int *string_
} }
return GEOHASH_OK; return GEOHASH_OK;
} }