MATLAB: Release structure

structure

Dear all:
I try to set a separate file for parameters in a model, and I want to retain their name so later on I can do sensitivity analysis using string comparison to identify the parameter name. So I define my parameters into structures, such as:
param.eps = 6;                         
param.beta = 0.99;                          
param.theta = 0.7532;                       
param.gamma = 0.5;
I want to release the structures into into variables as the following:
eps = 6;                         
beta = 0.99;                          
theta = 0.7532;                       
gamma = 0.5;
Is there an automatic way for doing this? I suspect I can setup the structure contains the name and value separately, and I probably can run a loop to equate the name with the value. But I think there must be a quicker and better way of doing this…
Any comments will be appreciated.
Cheers
Ben

Best Answer

Staying at the structs has some benefits if you use dynamic field names:
param.eps = 6;
param.beta = 0.99;
param.theta = 0.7532;
param.gamma = 0.5;
fields = fieldnames(param);
for i = 1:length(fields)
  aField = fields{i};
  fprintf('%s = %g\n', aField, param.(aField));
end
If you assign the variable "eps" dynamically, you will overwrite the built-in function with the same name. Such tricks will impede the debugging dramatically!
But if you really have a really good reason to need this really:
function FieldToVar(S)
F = fieldnames(S)
for i = 1:length(F)
  aF = F{i};
  assignin('caller', aF, S.(aF));
end
This is faster than an equivalent EVAL approach and less dangerous. Nevertheless, I think, this method is worse than using the dynamic field names directly.
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