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Use Standard Library Binary Search

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Replace handcoded binary search in RideFiletimeToDistance() method
in RideFile with lower_bounds, since it is more efficient. The
distanceToTime() method has been removed since it is not used.
This commit is contained in:
Mark Liversedge
2009-12-13 20:43:01 +00:00
committed by Sean Rhea
parent 74742965dd
commit a649f64655
2 changed files with 16 additions and 48 deletions
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61
src/RideFile.cpp
View File

@@ -72,6 +72,21 @@ RideFile::intervalBegin(const RideFileInterval &interval) const
return i - dataPoints_.begin();
}
double
RideFile::timeToDistance(double secs) const
{
RideFilePoint p;
p.secs = secs;
// Check we have some data and the secs is in bounds
if (dataPoints_.isEmpty()) return 0;
if (secs < dataPoints_.first()->secs) return dataPoints_.first()->km;
if (secs > dataPoints_.last()->secs) return dataPoints_.last()->km;
QVector<RideFilePoint*>::const_iterator i = std::lower_bound(dataPoints_.begin(), dataPoints_.end(), &p, ComparePoints());
return (*i)->km;
}
void RideFile::writeAsCsv(QFile &file, bool bIsMetric) const
{
@@ -199,49 +214,3 @@ void RideFile::appendPoint(double secs, double cad, double hr, double km,
dataPresent.alt |= (alt != 0);
dataPresent.interval |= (interval != 0);
}
double
RideFile::distanceToTime(double km) const
{
// inefficient but robust - iterate over points until
// you have gone past the km desired.
// rounded to the nearest data point - no smoothing
for (int i=0; i<dataPoints_.count(); i++) {
if (dataPoints_.at(i)->km >= km) return dataPoints_.at(i)->secs;
}
return 0;
}
double
RideFile::timeToDistance(double secs) const
{
// inefficient but robust - iterate over points until
// you have gone past the km desired.
// rounded to the nearest data point - no smoothing
RideFilePoint *midp, *leftp, *rightp;
if (dataPoints_.count() == 0) return 0;
int left =0;
int right=dataPoints_.count()-1;
int middle;
while (right-left > 1) {
middle = left + ((right - left ) / 2);
midp = dataPoints_.at(middle);
leftp = dataPoints_.at(left);
rightp = dataPoints_.at(right);
if (leftp->secs >= secs) return leftp->km;
if (rightp->secs <= secs) return rightp->km;
if (midp->secs == secs) return midp->km;
if (midp->secs > secs) right = middle;
else if (midp->secs < secs) left = middle;
}
// just in case it is between points
double leftdelta = secs - leftp->secs;
double rightdelta = rightp->secs - secs;
return (leftdelta > rightdelta) ? rightp->km : leftp->km;
}

3
src/RideFile.h
View File

@@ -121,8 +121,7 @@ class RideFile
void resetDataPresent();
double distanceToTime(double) const; // get distance km at time secs
double timeToDistance(double) const; // get time secs at distance km
double timeToDistance(double) const; // get distance in km at time in secs
};
struct RideFileReader {