Mercurial > octave
view scripts/miscellaneous/memoize.m @ 32047:e3de59065cf1
inputParser.m: Re-architect internal data structures for 60% speed improvement.
Key idea is to replace Parameter and Switch structs with name field containing
a nested struct (def, val fields) with a struct array that has fields "name",
"def", and "val". This makes it possible to eliminate for loops.
* NEWS.9.md: Announce performance improvement.
* inputParser.m: Declare "Parameter" and "Switch" properties as struct arrays.
Add new private property "last_idx" which caches the last Parameter or Switch
lookup.
* inputParser.m (addRequired): Adjust input validation to use numel() now
rather than numfields().
* inputParser.m (addOptional): Adjust input validation to use numel() now
rather than numfields().
* inputParser.m (addParameter): Change code to add new Parameter to a struct
array.
* inputParser.m (addSwitch): Change code to add new Switch to a struct
array.
* inputParser.m (parse): Adjust initialization of internal variables
ParameterNames and SwitchNames to match new data structure.
Use last_idx to simplify call to validate_arg() for Parameters.
* inputParser.m (validate_arg): Move creation of error message
to code path when error has been found---No need to do it for every
function call. Don't capture "exception" variable in try/catch as
it is no longer used.
* inputParser.m (is_argname): Cache "last_idx" if match was found.
* inputParser.m (add_missing): Replace call to setdiff() with in-place
code which can take advantage of implicit knowledge to eliminate calls
to unique and input validation. Replace for loop with cell2struct/struct2cell
combination.
author | Rik <rik@octave.org> |
---|---|
date | Fri, 21 Apr 2023 11:01:40 -0700 |
parents | 597f3ee61a48 |
children | 2e484f9f1f18 |
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######################################################################## ## ## Copyright (C) 2022-2023 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## This file is part of Octave. ## ## Octave is free software: you can redistribute it and/or modify it ## under the terms of the GNU General Public License as published by ## the Free Software Foundation, either version 3 of the License, or ## (at your option) any later version. ## ## Octave is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with Octave; see the file COPYING. If not, see ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{mem_fcn_handle} =} memoize (@var{fcn_handle}) ## ## Create a memoized version @var{mem_fcn_handle} of function @var{fcn_handle}. ## ## Each call to the memoized version @var{mem_fcn_handle} checks the inputs ## against an internally maintained table, and if the inputs have occurred ## previously, then the result of the function call is returned from the table ## itself instead of evaluating the full function again. This speeds up the ## execution of functions that are called with the same inputs multiple times. ## ## For example, here we take a slow user-written function named @code{slow_fcn} ## and memoize it to a new handle @code{cyc}. The first executions of both ## versions take the same time, but the subsequent executions of the memoized ## version returns the previously computed value, thus reducing 2.4 seconds of ## runtime to only 2.4 milliseconds. The final check verifies that the same ## result was returned from both versions. ## ## @example ## @group ## >> tic; @var{p} = slow_fcn (5040); toc ## Elapsed time is 2.41244 seconds. ## >> tic; @var{p} = slow_fcn (5040); toc ## Elapsed time is 2.41542 seconds. ## ## >> cyc = memoize (@@slow_fcn); ## >> tic; @var{r} = cyc (5040); toc ## Elapsed time is 2.42609 seconds. ## >> tic; @var{r} = cyc (5040); toc ## Elapsed time is 0.00236511 seconds. ## ## >> all (@var{p} == @var{r}) ## ans = 1 ## @end group ## @end example ## ## @seealso{clearAllMemoizedCaches} ## @end deftypefn function mem_fcn_handle = memoize (fcn_handle) if (nargin != 1) print_usage (); endif if (! is_function_handle (fcn_handle)) error ("memoize: FCN_HANDLE must be a function handle"); endif mem_fcn_handle = __memoize__ (fcn_handle); endfunction %!test %! fcn1 = memoize (@sin); %! assert (isa (fcn1, "matlab.lang.MemoizedFunction")); %! fcn1 (pi); %! fcn2 = memoize (@sin); %! fcn2 (2*pi); %! assert (isequal (fcn1, fcn2)); %!test %! fcn = memoize (@rand); %! a = fcn (); %! b = fcn (); %! assert (a, b); %! fcn2 = memoize (@rand); %! c = fcn2 (); %! assert (a, c); %!test %! fcn = memoize (@plus); %! fcn.stats; %! stats (fcn); %! clearCache (fcn); %! fcn.clearCache; ## Test input validation %!error <Invalid call> memoize (); %!error <FCN_HANDLE must be a function handle> memoize (1);