Concatinating multiple function outputs

7 views (last 30 days)
I have a few functions that each returns 3 output values, within a for loop using i as a counter. Is there a nice way to assign values, in the sense that i am currently using:
for i=1:n
[TestValues(i,1), assymp(1), names{1}] = ftesttype1(I(:,i),p,sign);
[TestValues(i,2), assymp(2), names{2}] = ftesttype2(I(:,i),p,sign);
As you can see i have manually labelled them 1 and 2 for their places. Is there a way such taht the output will automatically move to the right spot ? - Ie. after ftesttype1 has returned its values ftesttype2 will put them in the right place without me needing to specify that spot 2 is to be used in the vectors TestValues, assymp and names.
The thing is i have meaby 50 such functions and how many changes sort of often. So i have to manually retype some 150 numbers alot (and check that i have done so correctly).
Thanks ALOT in advance!
Thor on 21 Apr 2014
What I meant to communicate was that after the first function has placed its output, I need the second function to place its own output correctly.
In total I have meaby 50 function calls, each returning 3 output variables. And it all happens within the loop. What I need is Basically a way to recode this in such a way that I avoid manually retyping the test number (1,...,50) for each function called.
The reason I have to do so is partly to work faster, but also because I may need to publish some of the code and I am therefore trying to make it "nice" and flexible.
Thanks for taking an interest !

Sign in to comment.

Accepted Answer

Sean de Wolski
Sean de Wolski on 21 Apr 2014
Edited: Sean de Wolski on 21 Apr 2014
If you have a cell array containing your function handles, you could perhaps use cellfun to do the work for you:
Very simple example:
clear C % important for dynamic preallocation
funs = {@sin,@cos}; % function handles
vals = rand(1,50)*2*pi; % example values to loop over
for ii = numel(vals):-1:1
% Build anonymous function for each value and evaluate all functions at that value storing the result in the iith row of C
C(ii,:) = cellfun(@(x)x(vals(ii)),funs,'UniformOutput',false);
note 1 This also gives you the advantage of not necessarily having to input each function name. You could perhaps use dir to scrape a "functions to use" directory and then str2func to build the cell array automatically.
note 2 You don't need to use cellfun, but could use a loop instead. The key takeway here is the cell array containing the functions.
Thor on 23 Apr 2014
Thanks a bunch it is working! :)

Sign in to comment.

More Answers (1)

Walter Roberson
Walter Roberson on 20 Apr 2014
There is nothing in MATLAB similar to "use the above as an example".
Are all of the functions called the same way? If so then you can use
for K = 1 : 50 %build table of function handles
funtab{K} = str2fun(sprintf('ftesttype%d', K));
for i = 1 : n
for K = 1 : 50
TestValues(i, K), assymp(K), names{K}] = funtab{K}(I(:,i), p, sign);
Walter Roberson
Walter Roberson on 21 Apr 2014
Using a function table can account for calling the same function multiple times: just have multiple entries with the same handle.
Likewise you can use a cell array to hold all of the different inputs. You can do part of the breaking up of I(:,i) automatically by using mat2cell()
It might possibly be more convenient to reorder the calls so all of the ones with the same structure are done together. If the output order makes a difference for the remainder of your code, you could reorganize the outputs after the call loop.
Categorize and parameterize the calls as much as feasible. You can, for example, have a table which looks something like
output_number call_variety function_index parameter1_index
where call_variety is an index that tells you which variety of call it is, in the sense of which variables need to be passed.
I have, for example, written table-driven decompilers that mapped machine code byte into an "instruction format" code that knew (e.g.) that the instruction was a immediate-to-register instruction with specific offset and bit length encoding the destination register and specific offset and bit length encoding the "immediate" value; other instruction formats coded for register-to-register or condition-code bits and so on. The "variety" in the table encoded which kind of situation the entry should be treated as.

Sign in to comment.


Find more on Data Type Identification in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by