Assign rename of structure with input command

Hello

I am trying to make some of my scripts a bit more easy to use.I am stuck on the rename option of a structure combined with the input command.

What i would like to have is

file=input('Enter the name .dat e.g. "fname.dat" = ')
S = input('Enter a name for the structure = ...')
A=load(file);

S.H1 = A(:,2);
S.H2 = A(:,3);
S.H3 =A(:,4);

Something like that i have but it does not work

how can i finally use the input command in a way that will prompt me and alter the name of the structure?

thank you

[Sara]

Why do you need the user to input the structure name?

Answer 1

[Robert Cumming]

I also do not advocate the use of eval.

You could use "assignin", e.g.

S.H1 = A(:,2);
S.H2 = A(:,3);
S.H3 = A(:,4);
userName = 'ABC'; 
assignin ( 'base', userName, S ); this assuigns S to the variable name ABC

or put it in a sub function:

function AssignmentFunction ( S, userName )
  assignin ( 'caller', userName, S )
end

However I cant really think why you want to do this - if you explain in a bit more detail what your end goal is (how are you using these renamed variables) you will get better help...

Answer 2

[Evan]

You could use the eval command to do this, but eval can be problematic and usually should be avoided. If you were fine with using nested structures but keep a constant name for the outer structure, you could do this:

S = input('Enter a name for the structure = ...','s')
outerStruct.(S).H1 = rand

This way, you could avoid creating a variable from the string name but still allow some flexibility in structure naming. It would just be a little less neat looking.

[George]

In this case then i still use 'fname' when the input prompts me I am trying but the code does not operate for me.

S = input('Enter a name for the structure = ...','s')

S.Annual.PkDir;
S.Annual.Time=Time;

thank you

[Evan]

This is because you cannot create a variable (in this case a structure) name from a string in that way. You have to use the eval command, which is not recommended. In my example code, I make S the fieldname by using a dynamic field reference, which is why I place the S inside parenthesis.

Another user has submitted an example of how to do this with eval, but I have to agree with him that using it in conjunction with user input is quite risky.

[George]

Thank you for the answer that really helped, i am using the structures to store simulation data, for variables locations so the structure rename (a bit automated) will allow me to post process the large amount of data i have and create multiple main structures (with sub-structures inside) for every location and season, with out having to open the scipt and rename them

Answer 3

[Nir Rattner]

You can use the “eval” function to effectively convert a string to a variable name:

S=input('Enter a name for the structure = ','s');
eval([S '.H1=A(:,2)']);

That being said, “eval” is almost rarely the best choice because it is inefficient and risky (especially when combined with user input). Without knowing exactly what you are trying to do with the renamed struct, another possibility could be to use a wrapper struct and assign the renamed data as one of its fields:

S=input('Enter a name for the structure = ','s');
wrapper.(S).H1=A(:,2);

[George]

I am trying to store seasonal results from some simulations i have done, each sim has 8 outputs and those 8 are divided in months (each month has 8 variable) and there is an corresponding annual one