Unique? No.
Simple? Well, if you pick a model, e.g. linear, then there are various *Fit
functions that can construct a model.
lm = LinearModelFit[DeleteCases[Transpose@{B, A}, {_, ""}], b, b];
anew = Transpose@{B, A} /. {b_, ""} :> {b, lm@b} // Transpose // Last
(*
{190.59, 190.783, 190.985, 191.002, 191.008, 191.023, 191.029,
191.029, 191.05, 190.913, 190.925, 191.057, 190.964, 191.001,
191.061, 190.965}
*)
The result is disappointing on the example data supplied. Below I use the same method to fill in the missing value, but color the new point red:
Transpose@{B, A} /. {b_, ""} :> Style[{b, lm@b}, Red] // ListPlot
I suppose it's not actual data, since there appears to be no significant relationship between B
and A
. I would say in this example, there is no reliable way to fill in the missing values.