Compute virtual input and output for (standard) DEA model
For the given orientation, input, output and weights compute virtual input and output as described in @references A new approach to the bi-dimensional representation of the DEA efficient frontier with multiple inputs and outputscompute DMU's efficiencies
virtual_dea(input, output, orientation, ux, vy)
input: A matrix or a data frame containing the inputs of the units to be evaluated, with one row for each DMU and one column for each input.output: A matrix or a data frame containing the outputs of the units to be evaluated, with one row for each DMU and one column for each output.orientation: Use "input" for input orientation or "output" for output orientation in DEA model. The default is "input".vinput, voutput