51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
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#include "gtl_math_var.h"
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#include "gtl_math.h"
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namespace gtl {
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namespace math {
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var::var(gtl::analog_data *data)
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: analog_value(data)
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, _variance(0.)
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{
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_name = "var";
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}
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void var::before_copying_data(std::vector<qreal>::iterator begin, std::vector<qreal>::iterator end)
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{
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_variance -= variance(begin, end);
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}
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void var::after_copying_data(std::vector<qreal>::iterator begin, std::vector<qreal>::iterator end)
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{
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_variance += variance(begin, end);
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}
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void var::data_changed()
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{
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analog_value::data_changed();
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if(_data.size() != 0)
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_value = _variance;
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emit value_changed();
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}
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qreal var::variance(std::vector<qreal>::iterator begin, std::vector<qreal>::iterator end)
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{
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int n = std::distance(begin, end);
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qreal mean = std::accumulate(begin, end, 0.)/n;
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qreal v = 0.;
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for(auto it = begin; it != end; ++it)
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v += qPow((*it - mean), 2);
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v /= n-1;
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return v;
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}
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} // namespace math
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} // namespace gtl
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