Is there a Matlab conditional IF operator that can be placed INLINE like VBA's IIF

Solution 1:

How about simply using the fact that MATLAB automatically converts variable types when required by the operation? E.g., logical to double.

If your variables are scalar double, your code, I believe, can be replaced by

a = b + (c > 0) * c;

In this case, the operator (c > 0) values 1 (logical type) whenever c > 0 and values to 0 otherwise.

Solution 2:

There is no ternary operator in Matlab. You can, of course, write a function that would do it. For example, the following function works as iif with n-d input for the condition, and with numbers and cells for the outcomes a and b:

function out = iif(cond,a,b)
%IIF implements a ternary operator

% pre-assign out
out = repmat(b,size(cond));

out(cond) = a;

For a more advanced solution, there's a way to create an inline function that can even do elseif, as outlined in this blog post about anonymous function shenanigans:

iif  = @(varargin) varargin{2*find([varargin{1:2:end}], 1, 'first')}();

You use this function as

iif(condition_1,value_1,...,true,value_final)

where you replace the dots with any number of additional condition/value pairs.

The way this works is that it picks among the values the first one whose condition is true. 2*find(),1,'first') provides the index into the value arguments.

Solution 3:

There is no built-in solution for this, but you can write an IIF yourself.

function result=iif(cond, t, f)
%IIF - Conditional function that returns T or F, depending of condition COND
%
%  Detailed 
%     Conditional matrix or scalar double function that returns a matrix
%     of same size than COND, with T or F depending of COND boolean evaluation
%     if T or/and F has the same dimensions than COND, it uses the corresponding 
%     element in the assignment
%     if COND is scalar, returns T or F in according with COND evaluation, 
%     even if T or F is matrices like char array.
%
%  Syntax
%    Result = iif(COND, T, F)
%           COND - Matrix or scalar condition
%           T  - expression if COND is true
%           F  - expression if COND is false
%           Result - Matrix or scalar of same dimensions than COND, containing
%                    T if COND element is true or F if COND element is false.
%
if isscalar(cond) 
   if cond 
       result = t;
   else
       result = f;
   end
else
  result = (cond).*t + (~cond).*f;
end  
end

Solution 4:

Others have said already that there is no ternary ?: operator in Matlab. As a solution I suggest this function, which takes three functions instead of values. Therefore the amount of unnecessary calculations is minimized and you can check conditions before starting calculations, e.g. if a value is really numeric, or finite, or nonzero:

function [ out ] = iif( condition, thenF, elseF, in, out)
%iif Implements the ternary ?: operator
%   out = iif (@condition, @thenF, @elseF, in[, out])
%
%   The result is equivalent to:
%   condition(x) ? thenF(x) : elseF(x)
%
%   The optional argument out serves as a template, if the output type is
%   different from the input type, e.g. for mapping arrays to cells and
%   vice versa.
%
% This code is in the public domain.

mask = condition(in);
if nargin <= 4
  out = in;
end

if sum(mask)
  out(mask)  = thenF(in(mask));
end
if sum(~mask)
  out(~mask) = elseF(in(~mask));
end

end

Use it like this:

f = @(y)(iif(@(x)(x > 3), @(x)(x.^2), @(x)(x/2), y))
f(linspace(0,6,10))