De-duplicate code associated to time-series & time-series numbers

[flomnes]

• Binding constraints
• Links

Main PR: #1677

Idea

One shared TimeSeriesNumbers object, used by one or many TimeSeries objects.

TimeSeries can only be constructed from an existing TimeSeriesNumbers.

#include <vector>

class TimeSeriesNumbers {
public:
  int getTSNumber(int year) const {
      tsNumbers_[year];
  }
private:
  std::vector<int> tsNumbers_;
};

class TimeSeries {
public:
  TimeSeries(const TimeSeriesNumbers& tsNumbers) : tsNumbers(tsNumbers) {}
  double getCoefficient(int year, int hourInYear) {
      return coefficients[tsNumbers.getTSNumber(year)][hourInTheYear];
  }
private:
  Matrix<> coefficients;
  const TimeSeriesNumbers& tsNumbers;
};

// Thermique pour un cluster thermique
class ThermalCluster {
public:
  ThermalCluster() : availability(tsNumbers), marketBidCost(tsNumbers) {}

  TimeSeries availability;
  TimeSeries marketBidCost;
private:
  TimeSeriesNumbers tsNumbers;
};

// Hydro pour une zone
class Hydro {
public:
  Hydro() : ror(tsNumbers), ruleCurves(tsNumbers) {}

  TimeSeries ror;
  TimeSeries ruleCurves;
private:
  TimeSeriesNumbers tsNumbers;
};

void usage() {
  ThermalCluster cluster;
  cluster.availability.getCoefficient(year, hourInYear);
  cluster.availability.getColumn(year)[hourInTheYear];
  auto& avail = cluster.availability.getColumn(year);
  a = avail[hourInYear];
  Hydro hydro;
}

[flomnes]

Remove scratchpad.ts

[guilpier-code]

The previous code excerpt shows a way to remove code duplication.
Each time we use an instance of Class TimeSeries, we need a vector of TS numbers as well.
So a question arises : for cohesion reason, would it make sense to gather a TS and such a vector of TS numbers in the same class ?
If it does make sense, it would allow to remove to vector of TS from business classes (ThermalCluster, Hydro, ...).
We should take into account that the same vector of TS numbers can be shared among multiple TS.
Other question : is there a design pattern for this ?

[sylvlecl]

I suggest that:

• the series in "business" classes are not public (ror, ruleCurves, etc): otherwise they could be re-assigned after class construction, which will break the consistency with TS numbers
• "timeseries" is in general the word for only ONE column of data, we should probably find another name for the table (TimeseriesSet ?)
• since in the computation, the usage will be column-wise, we should expose the timeseries (column) themselves.
  I would be in favor of having a class for it, not only a double* as today, so that the typing and naming carry the meaning of those columns, like

class Timeseries
{
public:
    // either a getter or the operator as today
    double operator[](int hour) const { return values[hour]; }
private:
    int size;
    double* values;
};

[flomnes]

• the usage will be column-wise, we should expose the timeseries (column) themselves.
  I would be in favor of having a class for it

Why not using TimeSeries = std::vector<double> ? Note that the size is supposed to be shared across all timeseries (rectangular matrix)

We could also use Eigen's Matrix, which supports extracting a single column through Eigen::Matrix::col

[sylvlecl]

Why not using TimeSeries = std::vector<double> ? Note that the size is supposed to be shared across all timeseries (rectangular matrix)

Well it's of course a valid choice too:

• a small difference is that with a wrapper we can add wordings and documentation to carry more meaning for our usage (typically, we can say that the operator expects an "hour" or a "timestep", not just an "index"). And possibly utilities methods if needed in the future.
• on the other side, we don't automatically inherit of all vector operations.