What is the correct syntax to assign simulated data to my variables?

Dears,

I am running a MS-DSGE model using RISE toolbox. I want to add a fiscal shock and examine its effect on output, price...

%fiscal shock
shock_type = {'eps_G'};
%here is my variable list of a cell array of character variables and not a struct.  
var_list={'log_y','C','pi_ann','B_nominal','B','sp','i_ann','r_real_ann','P'};
% EXOGENOUS SWITCHING 
myirfs1=irf(m1,'irf_periods',24,'irf_shock_sign',1);
% following the suggestion by @VBBV, I use the following sintaxes to access elements of struct 
myirfs1 = struct()
myirfs1.eps_CP = struct();
myirfs1.eps_G = struct();
myirfs1.eps_T = struct();
myirfs1.eps_a = struct();
myirfs1.eps_nu = struct();
myirfs1.eps_z = struct();
var_aux = {'log_y','C','pi_ann','B_nominal','B','sp','i_ann','r_real_ann','P'};
var_aux3 = {'eps_G_log_y','eps_G_C','eps_G_pi_ann','eps_G_B_nominal','eps_G_B','eps_G_sp','eps_G_i_ann','eps_G_r_real_ann','eps_G_P'};
fieldnames(myirfs1)
myirfs1.eps_G.var = var_aux3  % assign the data array to the struct variable 
irf_fisc = struct();
for i = 1:numel(var_aux)
    irf_fisc.var_aux{i} = [0,myirfs1.eps_G.var{i}]';
end
irf_fisc.var_aux(1)
irf_fisc
% what is the write syntax to assign value (simulated data) to the struct?
myirfs1.eps_G.logy = data(:,1)/10;
%Is the suggested code. but where is the data variable located? should I create it
%data = randn(TMax, N); or it is already simulated?

Answer 1

[Epsilon]

Hi Gabriel,

In the provided code the variable ‘myirfs1’ is a structure array which is assigned different struct fields by using the syntax ‘myirfs1.eps_CP = struct();’. The variable ‘var_aux3’ is a cell array with the 9 set of cells containing strings.

Please note that the values in the cell array, eg: ‘log_y’,’C’,’pi_ann’,etc. are strings and not variables. Therefore, they cannot store any value instead the cell can be replaced by a new cell containing a different value.

It seems there is some confusion between the usage/syntax of cell arrays and structures. Please follow the link to the documentation on cell arrays and structures:

• https://www.mathworks.com/help/matlab/cell-arrays.html
• https://www.mathworks.com/help/matlab/structures.html

The documentation contains relevant links to assigning and accessing data in these datatypes.

Answer 2

[Voss]

This may be a useful reference:

G_var_list = {'log_y','C','pi_ann','B_nominal','B','sp','i_ann','r_real_ann','P'};
irfs_var_list = strcat('eps_',{'CP','G','T','a','nu','z'});

C = irfs_var_list;
C(end+1,:) = {struct()};
myirfs1 = struct(C{:});

myirfs1

myirfs1 = struct with fields:
    eps_CP: [1x1 struct]
     eps_G: [1x1 struct]
     eps_T: [1x1 struct]
     eps_a: [1x1 struct]
    eps_nu: [1x1 struct]
     eps_z: [1x1 struct]

myirfs1.eps_G

ans = struct with no fields.

C = G_var_list;
C(end+1,:) = {[]};
myirfs1.eps_G = struct(C{:});

myirfs1.eps_G

ans = struct with fields:
         log_y: []
             C: []
        pi_ann: []
     B_nominal: []
             B: []
            sp: []
         i_ann: []
    r_real_ann: []
             P: []

irf_fisc = struct();
for i = 1:numel(G_var_list)
    irf_fisc.(G_var_list{i}) = [0,myirfs1.eps_G.(G_var_list{i})].';
end
irf_fisc.(G_var_list{1})

ans = 0

irf_fisc

irf_fisc = struct with fields:
         log_y: 0
             C: 0
        pi_ann: 0
     B_nominal: 0
             B: 0
            sp: 0
         i_ann: 0
    r_real_ann: 0
             P: 0

https://www.mathworks.com/help/matlab/ref/struct.html

https://www.mathworks.com/help/matlab/matlab_prog/generate-field-names-from-variables.html