MATLAB: Removing parentheses around digits using regular expressions

Question

Dear all, I am slowly making progress on my learning of regular expressions. At the moment, I am trying to solve the following problem: replace all occurrences of (n) with n, where n is a number, provided that no alphabetical letter occurs before the first parenthesis. As an example,

 str='(2)+p_5*(3)-(0.3)'

would become

 2+p_5*3-0.3

I wrote the following

 regexprep(str,'(\W)(\()([.012345789]+)(\))','$1$3')

but it does not solves the problem if one of the expressions to change occurs at the beginning as in the example above. More concretely, the answer I get from running this is

 (2)+p_5*3-0.3

which is not the expected result.

Thanks in advance for any help

Pat.

Answer 1

regexprep(str,'(\()([\d*\.]+)(\))','$2')