concatenation of the arrayfun output

Question

Assuming that

outputTemp =

  2×1 cell array

    {122×1 string}
    {220×1 string}

finalOutput is a string array (342x1 string).

is there any way to do the following

outputTemp = arrayfun(@(x)someFunc(x), someInput, 'UniformOutput', false)';
finalOutput= [outputTemp{1}; outputTemp{2}];

in one line?

for the minimal example, someFunc can be a function that provides the names of the files in folders provided in someInput.

I see, I guess for using `cat` you would need another line, have you checked `cell2mat(arrayfun(...))`? — Irreducible, Jan 22 '20 at 07:57
"CELL2MAT does not support cell arrays containing cell arrays or objects." — Gideon Kogan, Jan 22 '20 at 08:00
Why does it need to be on one line? Is that really worth making stuff totally unreadable? Maybe there is a different solution to your problem that doesn’t require putting all of this on one line. Please share your actual problem! — Cris Luengo, Feb 05 '20 at 14:57

max · Answer 1 · 2020-01-22T08:33:16.393

Short answer: yes. Here is a MWE:

str1 = ["Test";"Test1";"42"]
str2 = ["new test";"pi = 3"]
C = {str1;str2}

ConCatStr = [C{1};C{2}];

This should answer the question regarding concatnation of string-arrays. Note that this is only possible with real strings (not with char-arrays). It is hard to tell, what you are doing beforehand as there are not details about getFilesFilt() and mainFolderCUBX.

EDIT MVE for the updated question

% function that returns a matrix
fnc = @(x)[x,1];
% anonymous function that returns a vector
fnc2 = @(x)reshape(fnc(x),2,1)

tmp = arrayfun(@(x)fnc(x), rand(10,1),'UniformOutput',false)

Answer: there is no proper way. However, you can do a little bit of fiddling and force everything into a single line (making the code ugly and less efficient)

tmp = arrayfun(@(x)fnc(x), rand(10,1),'UniformOutput',false);
out = reshape(cell2mat(tmp),numel(cell2mat(tmp)),1);

just replace the tmp with what is written with it.

My question was not phrased correctly, please review the question again and see if you can answer it. Your current answer is just a copy-paste of my code... — Gideon Kogan, Jan 22 '20 at 07:51
I am still missing a MVE. Regarding the requirement of 1-line command: In gerneal, no. Though the type-fun functions can return two arguments (e.g. if you say `arrayfun(@max,array)` it will return the maximum and the index as a second argument), there is no proper way in phrasing a non-uniform output directly into a single output. — max, Jan 22 '20 at 08:25

ThomasIsCoding · Answer 2 · 2020-01-22T09:01:06.513

0

You can try the following code using cat() + subsref(), i.e.,

finalOutput= cat(1,subsref(arrayfun(@(x)someFunc(x), someInput, 'UniformOutput', false),struct('type', '{}', 'subs', {{:}})));

Example

S(1).f1 = rand(3,5);
S(2).f1 = rand(6,10);
S(3).f1 = rand(4,2);

cat(1,subsref(arrayfun(@(x) mean(x.f1)',S,'UniformOutput',false),struct('type', '{}', 'subs', {{:}})))

such that

edited Jan 22 '20 at 09:01

answered Jan 22 '20 at 08:01

ThomasIsCoding

96,636
9
24
81

is it one-liner? does it save me a line? – Gideon Kogan Jan 22 '20 at 08:03
@GideonKogan what's your "someInput" and "someFunc()"? if no details, hard for others to give you one-liner command – ThomasIsCoding Jan 22 '20 at 08:11
it looks like it would work on python but your example does not work on my version. what is your version of the matlab? – Gideon Kogan Jan 22 '20 at 08:27
@GideonKogan I just ran it over Octave, not on MATLAB yet – ThomasIsCoding Jan 22 '20 at 08:28
please try on matlab – Gideon Kogan Jan 22 '20 at 08:29
@GideonKogan I don't have MATLAB on my laptop. I just want give you some ideas how to make it, but maybe you need to adapt it on your MATLAB. What's your MATLAB version? – ThomasIsCoding Jan 22 '20 at 08:30
2019a. I am familiar with this idea from python. it does not work on matlab. otherwise, there would be no questions – Gideon Kogan Jan 22 '20 at 08:36
@Irreducible what's is your Matlab version? – ThomasIsCoding Jan 22 '20 at 08:43
2018b, I am not aware that matlab supports function calls like these: `myfun(arg){:}` – Irreducible Jan 22 '20 at 08:46
sorry I think you missunderstood, I said: This WONT work on Matlab, also see this [answer](https://stackoverflow.com/questions/3627107/how-can-i-index-a-matlab-array-returned-by-a-function-without-first-assigning-it) – Irreducible Jan 22 '20 at 08:50
@Irreducible thanks for the link you leave in the comments. I updated my answer using `subsref`, so could you check if it works now? – ThomasIsCoding Jan 22 '20 at 09:02
it seems that `getfield` cant handle the colon operator (`{:}`), you get the following error `Invalid use of operator` – Irreducible Jan 22 '20 at 09:04
@Irreducible well....I cannot check it out by myself since I have no Matlab....but thank you any way – ThomasIsCoding Jan 22 '20 at 09:07

concatenation of the arrayfun output

2 Answers2