Fastest way to cycle through a structure for a number

given: a structure and a double
return: the index of a structure that has that number
data:
structure(1).val = 50
structure(2).val = 47
structure(3).val = 22
given: structure, 50
return: 1
given: structure, 22
return: 3
% my attempt
function y = return_struct_index(structure,inputval)
for i = 1:length(structure)
if structure(i).val==inputval
y = i;
return
end
end
y = [];
This is rather slow and comes in at about 2.5 seconds for 1000 iterations for my code. I know for a fact there is a faster way to do this but haven't been able to track it down. Obviously I haven't vectored my function. I have also tried converting the structure to a cell array and then vectoring the solution, but the conversion makes it even slower.
Help greatly appreciated!!
Will

1 Commento

If there are non-scalar arrays in the field val:
S(1).val = 50;
S(2).val = 47;
S(3).val = [23,5];
fun = @(n)find(arrayfun(@(s)any(s.val(:)==n),S));
>> fun(22)
ans =
Empty matrix: 1-by-0
>> fun(23)
ans =
3

Accedi per commentare.

 Risposta accettata

James Tursa
James Tursa il 1 Ago 2016
Modificato: James Tursa il 1 Ago 2016
result = find([structure.val]==value);
E.g.,
>> structure(1).val = 50;
>> structure(2).val = 47;
>> structure(3).val = 22;
>> find([structure.val]==50)
ans =
1
>> find([structure.val]==47)
ans =
2
>> find([structure.val]==22)
ans =
3
>> find([structure.val]==99)
ans =
Empty matrix: 1-by-0

1 Commento

Will Kinsman
Will Kinsman il 1 Ago 2016
Modificato: Will Kinsman il 1 Ago 2016
thanks so much. massively improved my programs performance by about 10 minutes. run time per 1000 iterations came in at about .5 seconds

Accedi per commentare.

Più risposte (1)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by