set order of elseif

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Rub Ron
Rub Ron 2020-12-17
评论： James Tursa 2020-12-17
Updated.
I have this code structure inside a loop. x, y and z are 1/0 variables. In this case the order of the elseif statement is: first x is evaluated, then y then z
if x
%code for case x
elseif y
%code for case y
elseif z
%code for case z
end
I would like to define a varible order (for the previous case order={'caseX','caseY','caseZ'}), where I can change the order in which the elseif statement is evaluated. So if I set order={'caseZ','caseX','caseY'}, I should get this: (first z is evaluated, then x then y)
order={'caseZ','caseX','caseY'}
%%% then
if z
%code for case z
elseif x
%code for case x
elseif y
%code for case y
end
An hint will be appreciated.
  2 个评论
Ive J
Ive J 2020-12-17
编辑：Ive J 2020-12-17
I'm not sure if I understood you correctly, but seems easier if you use switch/case. See here:
https://www.mathworks.com/help/matlab/ref/switch.html
KSSV
KSSV 2020-12-17
Have a look on switch.

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采纳的回答

James Tursa
James Tursa 2020-12-17
编辑：James Tursa 2020-12-17
Does this do what you want:
order = [1 2 3]; % or whatever
for k=1:numel(order)
switch order(k)
case 1
if( x )
% code for case x
break;
end
case 2
if( y )
% code for case y
break;
end
case 3
if( z )
% code for case z
break;
end
end
Or if you prefer the case selection could be for characters 'x', 'y', and 'z' instead of numbers 1, 2, 3.
The key is to have those break statements inside the cases so that the if-elseif-elseif control structure is emulated properly.
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Rub Ron
Rub Ron 2020-12-17
Thanks Bruno, I wish I can accept both answers at the same time, with only one click
James Tursa
James Tursa 2020-12-17
I gave Bruno a vote since he contributed a key part of the solution.

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更多回答（2 个）

Bruno Luong
Bruno Luong 2020-12-17
prefered_order = 'xzy';
b = [x y z]; % logical conditions (in if/elseif)
code_to_be_exec = { @xcode, @ycode, @zcode }; % code in the if elseif block put in functions
[~,i] = ismember(prefered_order, 'xyz');
j = find(b(i), 1, 'first');
if ~isempty(j)
feval(code_to_be_exec{i(j)});
end
  2 个评论
Rub Ron
Rub Ron 2020-12-17
do you think there is a way to preseve the if elseif structure? for easy-to-read purpose.
Bruno Luong
Bruno Luong 2020-12-17
编辑：Bruno Luong 2020-12-17
Of course, unroll all 6 possible permutations
if strcmp(prefered_order, 'xyz')
% your original if/else
elseif strcmp(prefered_order, 'yxz')
% another order...
elseif strcmp(prefered_order, 'zyx')
....
end

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KSSV
KSSV 2020-12-17
Are you looking something like this.
if z
%code for case z
order = ['case','z'] ;
elseif x
%code for case x
order = ['case','x'] ;
elseif y
%code for case y
order = ['case','y'] ;
end
  3 个评论
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KSSV
KSSV 2020-12-17
order = 'z'
if strcmpi(order,'z')
%code for case z
order = ['case','z'] ;
elseif strcmpi(order,'x')
%code for case x
order = ['case','x'] ;
elseif strcmpi(order,'y')
%code for case y
order = ['case','y'] ;
end
Also have a look on switch.
Rub Ron
Rub Ron 2020-12-17
I updated my post, hopefully now it is clearer.

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