common.cpp

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/*
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 *  Point Cloud Library (PCL) - www.pointclouds.org
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 * $Id: distances.cpp 527 2011-04-17 23:57:26Z rusu $
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#include <pcl/common/common.h>

void 
pcl::getMinMax (const sensor_msgs::PointCloud2 &cloud, int, 
                const std::string &field_name, float &min_p, float &max_p)
{
  min_p = FLT_MAX;
  max_p = -FLT_MAX;

  int field_idx = -1;
  for (size_t d = 0; d < cloud.fields.size (); ++d)
    if (cloud.fields[d].name == field_name)
      field_idx = static_cast<int>(d);

  if (field_idx == -1)
  {
    PCL_ERROR ("[getMinMax] Invalid field (%s) given!\n", field_name.c_str ());
    return;
  }

  for (unsigned int i = 0; i < cloud.fields[field_idx].count; ++i)
  {
    float data;
    // TODO: replace float with the real data type
    memcpy (&data, &cloud.data[cloud.fields[field_idx].offset + i * sizeof (float)], sizeof (float));
    min_p = (data > min_p) ? min_p : data; 
    max_p = (data < max_p) ? max_p : data; 
  }
}

void
pcl::getMeanStdDev (const std::vector<float> &values, double &mean, double &stddev)
{
  double sum = 0, sq_sum = 0;

  for (size_t i = 0; i < values.size (); ++i)
  {
    sum += values[i];
    sq_sum += values[i] * values[i];
  }
  mean = sum / static_cast<double>(values.size ());
  double variance = (sq_sum - sum * sum / static_cast<double>(values.size ())) / (static_cast<double>(values.size ()) - 1);
  stddev = sqrt (variance);
}