Reducing the size of a large script top speed onset of execution

Colleagues,

(R 2.10 on all platforms)

I have a lengthy script (18000 lines) that runs within a graphical interface. 
The script consists of 100's of function followed by a single command that 
calls these functions (execution depends on a number of environment variables 
passed to the script).  As a result, nothing is executed until the final line 
of code is read.   It takes 15-20 seconds to load the code - I would like to 
speed that process.  Two questions:

1.  The code contains numerous large blocks that are executed under only one 
set of conditions (which are known when the code is called).  For example, 
there might be code such as:
	if (CONDITION)
		{
		... (hundreds of lines of code, including embedded curly 
brackets)
		} else invisible()
	if (!CONDITION)
		{
		... (hundreds of lines of code, including embedded curly 
brackets)
		}
I assume that I could speed loading appreciably if I set up two scripts, each 
of which excluded "irrelevant" code depending on the CONDITION.  For example, 
if I knew that CONDITION was false, I would exclude the first block of code 
above; conversely, if I know that CONDITION was true, I would exclude the 
second block.

I would like to write code in R (or in sed [UNIX stream editor]) to create 
these two new scripts.  However, the regular expressions that would be needed 
are beyond me and I would appreciate help from this forum.  Specifically, I 
would like to search for:
	if (CONDITION 
or
	if (!CONDITION
as the start of the block and
	} - the matching curly bracket
at the end of the block, then remove those lines from the code.  These text 
entries are always on a line by themselves.  Finding the "if (CONDITION" line 
should be relatively easy.  The difficulty for me is identifying the matching 
curly bracket - there are often paired brackets within the block of code:

	if (CONDITION)
		{
		...
		if (SOMETHINGELSE)	{	}
		if (YETANOTHER)
			{
			}
		}				<-  this is the bracket that 
I need to match

There are also instances in which the entire block occurs on one line:
	if (CONDITION)	{ ...} else invisible()
or
	if (CONDITION ... else invisible()

Of note, I can remove the "else invisible() statements if they are 
problematic to a solution.

2.  A related issue regards loading in the graphical interface vs. loading at 
the command line (OS X).  The graphical interface loads in 15-20 seconds - 
the graphical interface is sending code as rapidly as it can.  In contrast, 
at the command line, the course is source()'d and it takes 30-40 seconds.  I 
would have expected the latter approach to be as fast or faster because R 
would accept code as fast as it could.

Does anyone have an explanation for this behavior; also, any ideas as to how 
to speed the process at the command line would be appreciated.  Thanks for 
any suggestions.

Dennis




Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com