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Calculate effective basezoom and droprate, taking gamma into account

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This commit is contained in:
Eric Fischer 2015-12-17 17:16:04 -08:00
parent acd4444439
commit 4fe1a950f5
1 changed files with 30 additions and 2 deletions
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32
geojson.c
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@ -1176,9 +1176,7 @@ int read_json(int argc, char **argv, char *fname, const char *layername, int max
basezoom = 0;
for (z = 0; z <= maxzoom; z++) {
// printf("%d/%u/%u has %lld ", z, max[z].x, max[z].y, max[z].count);
double zoomdiff = log((long double) max[z].count / max_features) / log(droprate);
// printf("which implies that base zoom should be %f\n", zoomdiff + z);
if (zoomdiff + z > basezoom) {
basezoom = ceil(zoomdiff + z);
}
@ -1201,6 +1199,36 @@ int read_json(int argc, char **argv, char *fname, const char *layername, int max
}
}
if (gamma > 0) {
int effective = 0;
for (z = 0; z < maxzoom; z++) {
if (max[z].count < max[z].fullcount) {
effective = z + 1;
}
}
if (effective == 0) {
fprintf(stderr, "With gamma, effective base zoom is 0, so no effective drop rate\n");
} else {
double interval_0 = exp(log(droprate) * (basezoom - 0));
double interval_eff = exp(log(droprate) * (basezoom - effective));
if (effective > basezoom) {
interval_eff = 1;
}
double scaled_0 = max[0].count / interval_0;
double scaled_eff = max[effective].count / interval_eff;
double rate_at_0 = scaled_0 / max[0].fullcount;
double rate_at_eff = scaled_eff / max[effective].fullcount;
double eff_drop = exp(log(rate_at_eff / rate_at_0) / (effective - 0));
fprintf(stderr, "With gamma, effective base zoom of %d, effective drop rate of %f\n", effective, eff_drop);
}
}
munmap(map, indexpos);
}