Formating a structs value

Question

sverre Kvist 2024-4-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2104791-formating-a-structs-value

评论： sverre Kvist 2024-4-10

采纳的回答： Aquatris

在 MATLAB Online 中打开

Hi!

i'm looking for a way to format the values fields in a struct to double.

The problem is that the variable names changes for each use-case. and i can't figure out how to write the part to format the structs value with varying variable names.(Clarifications in whole code below).

Example:

in essens i want to be able to use: double(answer.v1) but make it so that it accepts varying variables. i.e. double(answer.[variable-name-here]) (this is meant to visualize the problem, i know i can't use a struckt field call directly as shown in the example)

Current Data:

answer =

struct with fields:

v1: 9.9444846729423123340574462949553 + 0.31860970311368573497465604634323i

v2: 1.7861453053342988172821626840454 - 0.39584841902003379193820902727492i

Wanted Data:

double(answer.v1)

ans =

9.9445 + 0.3186i

double(answer.v2)

ans =

1.7861 - 0.3958i

Whole Code:

clc, clear, close all;
 % Example equation 1: (12-v1)/500 == (v1/10e3i) + (v1-v2)/2e3
 % Example equation 2: (v1-v2)/2e3 == v2/(-5e3i) + 4e-3
 % variables used: v1 v2
prompt = {'Number of Equations:','Number  of variables:'};
dlgtitle = 'Calc. of Node Voltage:';
dims = [1 50];
definput = {'2','2'};
nodeEquations = inputdlg(prompt,dlgtitle,dims,definput); %prompt user for number of variables and equations
%Input for number of variables
for i=1:numel(zeros(1,str2double(nodeEquations(2))))
    vartemp{i} = 'Unknown (Exact match to Equations!)';     % Creates temporary array for each unknown variable
end
%Input for number of equations
for i=1:numel(zeros(1,str2double(nodeEquations(1))))
    temparr{i} = 'Equation (Exact match to Unknown variables!)';    % Creates a temporary array for each equation
end
x = inputdlg(temparr);  %Prompts user for the equations
y = inputdlg(vartemp);  %Prompts user for Unknown variables
symbols = cell2sym(y);
equations = str2sym(x);
answer = solve(equations)

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Stephen23 2024-4-9

Perhaps either

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

or

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

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Answer 1

Aquatris 2024-4-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2104791-formating-a-structs-value#answer_1438726

编辑：Aquatris 2024-4-9

在 MATLAB Online 中打开

Something like this maybe:

syms v1 v2 ;
symbols = [v1;v2];
equations = [3/125 - v1/500 == v1*(0.0005 - 0.0001i) - 0.0005*v2
    0.0005*v1 - 0.0005*v2 == 0.004 + v2*0.0002i];
answer = solve(equations);
% get all the field names within 'answer'
fNames = fieldnames(answer);
% convert solution to doubles and store in 'sol' variable
for i = 1:length(fNames)
    sol.(fNames{i}) = double(answer.(fNames{i}));
end
sol
sol = struct with fields:
    v1: 9.9445 + 0.3186i
    v2: 1.7861 - 0.3958i