How to improve the execution time of my VI?

Question

My vi does data processing for hundreds of files and takes more than 20 minutes to commplete. The setup is firstly i use the directory LIST function to list all the files in a dir. to a string array. Then I index this string array into a for loop, in which each file is opened one at a time inside the loop, and some other sub VIs are called to do data analysis. Is there a way to improve my execution time? Maybe loading all files into memory at once? It will be nice to be able to know which section of my vi takes the longest time too. Thanks for any help.

Answer 1

Bryan,
If "read from spreadsheet file" is the main time hog, consider dropping it! It is a high-level, very multipurpose VI and thus carries a lot of baggage around with it. (you can double-click it and look at the "guts" )
If the files come from a just executed "list files", you can assume the files all exist and you want to read them in one single swoop. All that extra detailed error checking for valid filenames is not needed and you never e.g. want it to popup a file dialog if a file goes missing, but simply skip it silently. If open generates an error, just skip to the next in line. Case closed.
I would do a streamlined low level "open->read->close" for each and do the "spreadsheet string to array" in your own code, optimized to the exact format of your files. For example, notice that "read from spreadheet file" converts everything to SGL, a waste of CPU if you later need to convert it to DBL for some signal processing anyway.
Anything involving formatted text is not very efficient. Consider a direct binary file format for your data files, it will read MUCH faster and take up less disk space.
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