Use string to define variable
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Hello guys!
I am looking for a way to name a variable with a string name that will be changing according to the T and V values
My code is the following:
-------------------------------
T=15; % input variable T
V=1; % input variable V
load('FRF_T15_V1.mat')
load('FRF_T15_V2.mat')
load('FRF_T15_V3.mat')
formatSpec = 'FRF_T%d_V%d';
filename = sprintf(formatSpec,T,V);
x=eval(filename);
XP=(x{3,3});
save ('XP,'XP')
-----------------------------
I would like for variable XP to be assigned according to the input values of T and V, e.g.,
FRF_T15_V1_XP=(x{3,3});
And then save it as
save (' FRF_T15_V1_XP,' FRF_T15_V1_XP ')
Thanks in advance for your help!
Kind regards,
Hugo
采纳的回答
Storing meta-data in variable names (or fieldnames) is a very bad way to design your data, which invariably forces you into writing slow, complex, inefficient code that is much harder to debug than if you stored that meta-data as data in a variable (because meta-data is data):
But if you insist on this anti-pattern data design, something like this is probably the least-worst way of doing it:
T = 15;
V = 1;
F = sprintf('FRF_T%d_V%d',T,V);
S = load([F,'.mat']);
C = struct2cell(S);
X = C{1};
S = struct([F,'_XP'],{X{3,3}});
save([F,'_XP.mat'],'-struct',S)
However, treating meta-data as data in its own right (which it is) would be much better data design (it would make your code simpler, more robust, and more efficient).
See also:
3 个评论
Hugo Policarpo
2025-8-9
Hugo Policarpo
2025-8-9
Stephen23
2025-8-9
"your just missing a " ] " in the last line."
Thank you, I fixed that.
更多回答（3 个）
Steven Lord
2025-8-9
1 个投票
Can you dynamically create variables with numbered names like x1, x2, x3, etc.? Yes.
Should you do this? The general consensus is no. That Discussions post explains why this is generally discouraged and offers several alternative approaches.
There are many ways to do this. Here's one that shows how to make the format of the T and V values have the same width and will sort based on the value of T in the directory. Just change the '%n.n' to the largest width of your number range:
% for the character array version
fname = @(t,v) ['FRF_T' num2str(t,'%3.3d') '_V' num2str(v,'%2.2d') '_XP'];
for T=[1 3 5]
for V=1:2
fprintf(1,'%s\n', fname(T,V));
end
end
% for the string version
strfname = @(t,v) strcat("FRF_T", num2str(t,'%3.3d'), "_V", num2str(v,'%2.2d'), "_XP");
for T=[1 3 5]
for V=1:2
fprintf(1,'%s\n', strfname(T,V));
end
end
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