Re^3: Processing values of a piddle (PDL) speedup using 'at' vs. 'index'

I take values from these pdls, check them to see if they are a special value, change the value if needed, and then put them into a perl array.

I would say that is entirely the wrong way to do it.

You need to export the piddle in order to print it. So export it first; then search that for your special values; and only access the piddle elements individually if you find the special value in the exported array -- just to update it with the new value.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

Comment on Re^3: Processing values of a piddle (PDL) speedup using 'at' vs. 'index'

Replies are listed 'Best First'.
Re^4: Processing values of a piddle (PDL) speedup using 'at' vs. 'index' by kevbot (Vicar) on Jul 18, 2012 at 04:37 UTC
I agree (but my actual use case is a little more complex than the code examples that I have given here). I added an additional subroutine to my benchmark code to see how much faster your suggested approach would be. In the 'perl_array' sub, I export the entire pdl to a perl array using the PDL 'list' command. Then, I search the perl array for the "special value" and replace them with an empty string. This is approach is faster. Read more... (2 kB) `Rate pdl_values perl_values perl_array pdl_values 1.52/s -- -97% -99% perl_values 52.3/s 3345% -- -73% perl_array 197/s 12865% 276% --` [download]	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^4: Processing values of a piddle (PDL) speedup using 'at' vs. 'index'
by kevbot (Vicar) on Jul 18, 2012 at 04:37 UTC

I agree (but my actual use case is a little more complex than the code examples that I have given here). I added an additional subroutine to my benchmark code to see how much faster your suggested approach would be. In the 'perl_array' sub, I export the entire pdl to a perl array using the PDL 'list' command. Then, I search the perl array for the "special value" and replace them with an empty string. This is approach is faster.