How can I implement an array of function handles that takes a struct as input and calculates the function value for each function handle?
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Carolin Katzschke
am 2 Jun. 2015
Kommentiert: Carolin Katzschke
am 2 Jun. 2015
I have function handles, e.g. area_rectangle and area_circle, and structs that contain information like input_variables.height = 3.
function area_rectangle = area_rectangle(input_variables, constants)
if ~isfield(input_variables,'height') || ~isfield(input_variables,'width')
area_rectangle = NaN;
else
area_rectangle = input_variables.width * input_variables.height;
end
function area_circle = area_circle(input_variables, constants)
if ~isfield(input_variables,'radius') || ~isfield(constants,'pi')
area_circle = NaN;
else
area_circle = constants.pi * input_variables.radius^2;
end
Unfortunately, cell arrays can't be used because they need some kind of index support:
>> test = cell(2,1)
test =
[]
[]
>> test{1}=@area_rectangle;
>> test{2}=@area_circle;
>> test
test =
@area_rectangle
@area_circle
>> input_variables = struct('height',3,'width',2,'radius',1)
input_variables =
height: 3
width: 2
radius: 1
>> constants = struct('pi',3.14159)
constants =
pi: 3.1416
>> test(input_variables,constants)
Error using subsindex
Function 'subsindex' is not defined for values of class 'struct'
How can I use function handles and structs at the same time?
Thanks in advance.
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Akzeptierte Antwort
Jan Orwat
am 2 Jun. 2015
Hello Carolin, you can evaluate functions in a loop:
>> values = zeros(1,length(test));
>> for k = 1:length(test)
values(k) = test{k}(input_variables,constants);
end
>> values
values =
6.0000 3.1416
or using cellfun():
>> values = cellfun(@(F)F(input_variables,constants),test)
values =
6.0000 3.1416
cellfun looks more compact, but it is often harder to read and modify, especially when you are going back to the piece of code after a while.
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