Matlab separate output into 2 variables

Question

I have two float variables:

x = 0.5;
y = 1.5;

I would like to floor them:

x = floor(x);
y = floor(y);

Can i do it in a single command? this raises an error:

[x y] = floor([x y]);

Nothing really in particular... but this is a general question that can be applied to another usage. Don't focus on x, y — dynamic, Nov 30 '12 at 14:22
Then why not use `z = floor([x y])`? It's bound to be faster than @H.Muster's solution...If you must, just do `x = z(:,1), y = z(:,2)` at some point. — Rody Oldenhuis, Nov 30 '12 at 14:24
Like @RodyOldenhuis, I would also prefer the clean `floor` version over the wrapper I posted below to answer what the OP specifically asked for. — H.Muster, Nov 30 '12 at 14:27

score 7 · Accepted Answer · answered Nov 30 '12 at 14:21

You can write your own wrapper for floor:

function varargout = myFloor(varargin)
for k = 1:nargin
    varargout{k} = floor(varargin{k});
end

This function shows the required behavior if you provide x and y as two separated arguments

[a, b] = myFloor(x,y)

This results in

If you want to use the concatenated array [x y] as input (like in your example) you can use the following function:

function varargout = myFloor(x)
for k = 1:numel(x)
    varargout{k} = floor(x(k));
end

Then you would call

[a, b] = myFloor([x y])

This results in

score 2 · Answer 2 · answered Nov 30 '12 at 14:36

2

Just adding a random idea here...

Building on H.Muster solution, you might want to define a personalized deal function, which is like deal but also applies a function to each argument:

function varargout = myDeal(fun, varargin)
    if nargin == 2
        varargout(1:nargout) = {feval(fun, varargin{1})};
    elseif nargin-1 == nargout
        for k = 1:nargout
            varargout{k} = feval(fun, varargin{k}); end
    else
        error('Argument count mismatch.');
    end
end

This way, you can multi-assign any function:

>> [x,y,z] = myDeal(@floor, 0.5, 0.6, 2.7)
x =
     0
y =
     0
z =
     2

>>  [x,y,z] = myDeal(@sin, pi/6)
x =
     4.999999999999999e-01
y =
     4.999999999999999e-01
z =
     4.999999999999999e-01

>> [a, b] = myDeal(@fix, 10*rand(2), 8*rand(5))         
a =
     7     2
     7     6
b =
     5     2     4     1     6
     1     4     5     1     1
     0     1     7     2     7
     3     6     7     6     2
     7     2     4     2     1

answered Nov 30 '12 at 14:36

Rody Oldenhuis

37,726
7
50
96

@yes123: It will not be fast, at least, not as fast as doing things the vectorized way. Therefore I'd advise against using this in any "production code" or in performance-sensitive areas. – Rody Oldenhuis Nov 30 '12 at 15:12
1

@yes123: a similar idea can be found in the function `disperse` [on the File Exchange](http://blogs.mathworks.com/pick/2012/03/02/when-deal-doesnt-work-disperse-2/) – Jonas Nov 30 '12 at 15:18
@Jonas: yes, I thought as much...truly new ideas are rare :) – Rody Oldenhuis Nov 30 '12 at 16:12
@Jonas: Ah! But `disperse` doesn't pass things through functions, like the one above! :) – Rody Oldenhuis Nov 30 '12 at 16:14

score 1 · Answer 3 · answered Nov 30 '12 at 14:13

1

No it is not possible.
Floor can only accept one argument as it can be seen from the syntax. You can see the reference below to verify:

http://www.mathworks.in/help/symbolic/mupad_ref/floor.html

answered Nov 30 '12 at 14:13

Fyre

1,180
8
12

score 0 · Answer 4 · answered Nov 30 '12 at 14:14

0

if

    A = [0.5 1.5]

then you can do

    floor(A)

that would result in

    ans = [0 1]

Here's an example: http://www.matlabtutorials.com/functions/floor.html

answered Nov 30 '12 at 14:14

Rodrigo Neves

220
2
12

I need the results to be in the x and y var in a single command if it's possible – dynamic Nov 30 '12 at 14:15
Then the answer is no. As Fyre said, floor() can only take one argument, which can in fact be a vector, but it will return a vector back. – Rodrigo Neves Nov 30 '12 at 14:16

Matlab separate output into 2 variables

4 Answers4