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// This is mul/mbl/mbl_stats_nd.cxx
#include "mbl_stats_nd.h"
//:
// \file
// \brief Simple statistics (mean, variance) on vectors.
// \author Tim Cootes
#include <vcl_cmath.h>
#include <vcl_cassert.h>
#include <vcl_iostream.h>
#include <vnl/io/vnl_io_vector.h>
mbl_stats_nd::mbl_stats_nd()
{
clear();
}
void mbl_stats_nd::clear()
{
n_obs_ = 0;
sum_.set_size(0);
sum_sq_.set_size(0);
}
void mbl_stats_nd::obs(const vnl_vector<double>& v)
{
unsigned n=v.size();
if (n_obs_ == 0)
{
sum_ = v;
sum_sq_.set_size(n);
for (unsigned i=0;i<n;++i) sum_sq_[i]=v[i]*v[i];
n_obs_++;
return;
}
assert(v.size()==n);
sum_ += v;
for (unsigned i=0;i<n;++i) sum_sq_[i]+=v[i]*v[i];
n_obs_++;
}
vnl_vector<double> mbl_stats_nd::mean() const
{
if (n_obs_==0) return vnl_vector<double>();
else return sum_/n_obs_;
}
vnl_vector<double> mbl_stats_nd::variance() const
{
if (n_obs_==0) return vnl_vector<double>();
unsigned n=sum_.size();
vnl_vector<double> var(n);
if (n_obs_==1) { var.fill(0.0); return var; }
for (unsigned i=0;i<n;++i)
{
var[i] = (sum_sq_[i]-(sum_[i]*sum_[i]/n_obs_))/(n_obs_-1);
}
return var;
}
vnl_vector<double> mbl_stats_nd::sd() const
{
if (n_obs_==0) return vnl_vector<double>();
unsigned n=sum_.size();
vnl_vector<double> sd(n);
if (n_obs_==1) { sd.fill(0.0); return sd; }
for (unsigned i=0;i<n;++i)
{
double var = (sum_sq_[i]-(sum_[i]*sum_[i]/n_obs_))/(n_obs_-1);
if (var<=0) sd[i]=0.0;
else sd[i]=vcl_sqrt(var);
}
return sd;
}
vnl_vector<double> mbl_stats_nd::stdError() const
{
if (n_obs_==0) return vnl_vector<double>();
unsigned n=sum_.size();
vnl_vector<double> se(n);
if (n_obs_==1) { se.fill(0.0); return se; }
for (unsigned i=0;i<n;++i)
{
double var = (sum_sq_[i]-(sum_[i]*sum_[i]/n_obs_))/(n_obs_-1);
if (var<=0) se[i]=0.0;
else se[i]=vcl_sqrt(var/n_obs_);
}
return se;
}
mbl_stats_nd& mbl_stats_nd::operator+=(const mbl_stats_nd& s1)
{
sum_ += s1.sum();
sum_sq_ += s1.sumSq();
n_obs_ += s1.n_obs();
return *this ;
}
const double MAX_ERROR = 1.0e-8;
//: Test for equality
bool mbl_stats_nd::operator==(const mbl_stats_nd& s) const
{
if (n_obs_==0 && s.n_obs()==0) return true;
return n_obs_==s.n_obs() &&
vnl_vector_ssd(sum_,s.sum())/n_obs_<MAX_ERROR &&
vnl_vector_ssd(sum_sq_,s.sumSq())/n_obs_<MAX_ERROR;
}
//: Version number for I/O
short mbl_stats_nd::version_no() const
{
return 1;
}
void mbl_stats_nd::b_write(vsl_b_ostream& bfs) const
{
vsl_b_write(bfs,version_no());
vsl_b_write(bfs,n_obs_);
if (n_obs_==0) return;
vsl_b_write(bfs,sum_);
vsl_b_write(bfs,sum_sq_);
}
void mbl_stats_nd::b_read(vsl_b_istream& bfs)
{
if (!bfs) return;
short file_version_no;
vsl_b_read(bfs,file_version_no);
switch (file_version_no)
{
case 1:
vsl_b_read(bfs,n_obs_);
if (n_obs_<=0) clear();
else
{
vsl_b_read(bfs,sum_);
vsl_b_read(bfs,sum_sq_);
}
break;
default:
vcl_cerr << "I/O ERROR: mbl_stats_nd::b_read(vsl_b_istream&)\n"
<< " Unknown version number "<< file_version_no << '\n';
bfs.is().clear(vcl_ios::badbit); // Set an unrecoverable IO error on stream
return;
}
}
void mbl_stats_nd::print_summary(vcl_ostream& os) const
{
os << "mbl_stats_nd: ";
if (n_obs_==0)
os << "No samples.";
else
{
os << "mean: "<< mean();
}
}
vcl_ostream& operator<<(vcl_ostream& os, const mbl_stats_nd& stats)
{
stats.print_summary(os);
return os;
}
//: Stream output operator for class reference
void vsl_print_summary(vcl_ostream& os,const mbl_stats_nd& stats)
{
stats.print_summary(os);
}
mbl_stats_nd operator+(const mbl_stats_nd& s1, const mbl_stats_nd& s2)
{
mbl_stats_nd r = s1;
r+=s2;
return r;
}
//: Binary file stream output operator for class reference
void vsl_b_write(vsl_b_ostream& bfs, const mbl_stats_nd& b)
{
b.b_write(bfs);
}
//: Binary file stream input operator for class reference
void vsl_b_read(vsl_b_istream& bfs, mbl_stats_nd& b)
{
b.b_read(bfs);
}
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