I have a vector of structs each having a field x:
s1.x = 1;
s2.x = 2;
s3.x = 3;
S = [s1, s2, s3];
I would like to set the field x of all structs in S from a given vector X, i.e. I would like to vectorize the following loop:
X = [97, 98, 99];
for i = 1 : length(S)
S(i).x = X(i);
end
Is this possible?
You can do it this way:
Xc = num2cell(X); %// convert X to cell array of numbers
[S.x] = Xc{:}; %// generate comma-separated list from cell array, and assign
For Matlab versions before 7.0 the second line should be changed into
[S.x] = deal(Xc{:}); %// generate comma-separated list from cell array, and assign
[S.x] = X doesn't? Sometimes this vectorization stuff seems a little bit like voodoo to me.
deal if we're dealing with cell arrays, so just do it like: [S.x] = Xc{:};
Xc{:} is a comma-separated list. Simply converting to another data structure in between to get it done. @Luis Mendo: deal could be removed to get an even shorter solution.
deal I guess... Thanks!deal, but with cell arrays you can omit it. I figured it may save some clock cycles, but the deal is certainly more explicit!If you know the values in advance, you can initialize like this:
S = struct('x', {1 2 3})
S already exists, and I want to replace all the x fields at once from the vector X.