[R] formula substitution by its calculated value

[BOISSON, Pascal]

Dear R_Users,

I am confronted to a technical issue that I wouldn't even know how to start to handle and where to look at. It is about data manipulation in a dataframe and value substitution
Imagine I have a matrix describing a set of chemical equations. 
Colnames are Components names and Rownames are Reaction names

Each cell in that matrix corresponds to the stoechiometric coefficient to the pair (Reaction, Component). It would be easy to deal with this if these cells where filled with numbers (int or real) but often, it refers to some parameters name or even to formulae.

I'd like to transform these formulae into their calculated values.
eg: 
if I have existing R objects :
f_ox <- 0.2
f_inox <- 0.5

and in my matrix : 
cell (Oxydation, substrate) = f_ox*(1-f_inox)

I want to replace f_ox*(1-f_inox) by 0.1

Further more, I can not manage to understand the formula type, which I guess would correspond to the kind of things I am dealing with.

Would you have any clue or insights on this?

Pascal Boisson

Assainissement - Traitement Biologique
Veolia Environnement - Centre de Recherche sur l'Eau
Anjou Recherche
Chemin de la Digue - BP 76
78603 Maisons Laffitte Cedex
Tel. :  +33 (0)1 34 93 81 44
Fax. : +33 (0)1 34 93 31 10
pascal.boisson at veolia.com
 
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