computeMetrics_onScalar: computeMetrics_onScalar
In pyCGM2/rCGM2:

compute basic metrics between two modalities of the independant variable (\textbfComparisonFactor) for a specific Scalar

1 2	computeMetrics_onScalar(table, metricsFunction, DiscreteLabel, modality1, modality2, comparisonLabel = NULL)

`table`	[dataframe] all-cycle table
`metricsFunction`	[string] metrics ( eg, mae, rmse) to apply
`modality1`	[string] 1st selected modality of the independant variable (ComparisonFactor)
`modality2`	[string] 2nd selected modality of the independant variable (ComparisonFactor)
`comparisonLabel`	[string] label given to the comparison