Create a series of variables with names that include numbers

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Rich006 2023-4-28

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https://ww2.mathworks.cn/matlabcentral/answers/1954689-create-a-series-of-variables-with-names-that-include-numbers

编辑： Stephen23 2023-4-29

I need to create some fake data for testing a program. The fake data is a series of variables with names like VAR004300, VAR004400, VAR004500, etc. Each variable will be a 1x1 struct with 5 fields (same 5 fields for all variables). What is the smart way to create these variables? I would like to avoid typing out the field names the same way dozens of times. The dumb way:

VAR004300 = struct('FIELD1', value431, 'FIELD2', value432, ...);
VAR004400 = struct('FIELD1', value441, 'FIELD2', value442, ...)

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Rich006 2023-4-28

Thanks, but as I commented in the accepted answer, I'm trying to create a test data sample with these variable names and I was looking for an efficient way to create them all without having to type them all in.

Stephen23 2023-4-29

编辑：Stephen23 2023-4-29

"I was looking for an efficient way to create them all without having to type them all in."

Sure, that was perfectly clear from your question. And as everyone here was explaining, there is no "efficient way" to do that. Not only that, forcing meta-data into variable names makes processing data much harder, slower, and buggier, so the whole approach should be avoided anyway. Which is exactly what the links you were given explain.

The simpler, easier, and much more efficient approach is to use one array. Exactly what kind of array is best depends on the specific situation.

If you really are interested in "efficient" ways of storing and working with data, then understand that meta-data is data, and that data should be stored in variables (not in variable names or fieldnames). Then you can really start to write neat, robust, efficient, generalizable code:

https://www.mathworks.com/matlabcentral/answers/473601-looping-through-different-fields-in-struct#comment_728691

https://www.mathworks.com/matlabcentral/answers/451710-loop-through-specific-strcuture-field-names#comment_684375

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Answer 1

John D'Errico 2023-4-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1954689-create-a-series-of-variables-with-names-that-include-numbers#answer_1225304

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

The funny thing is, what you want to do actually is the bad way to solve the problem.

Instead, learn to use arrays. Learn to use cell arrays, instead of dynamically naming your variables.

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Steven Lord 2023-4-28

在 MATLAB Online 中打开

Then don't create them as "standalone" variables. Create them as fields of a base struct array then save the struct using the -struct option to write each field as a separate variable in the file. Then when you load the file with an output that will recreate that "base struct array".

cd(tempdir)
for k = 1:5
    data.("x" + k) = (1:10).^k;
end
data
data = struct with fields:
    x1: [1 2 3 4 5 6 7 8 9 10]
    x2: [1 4 9 16 25 36 49 64 81 100]
    x3: [1 8 27 64 125 216 343 512 729 1000]
    x4: [1 16 81 256 625 1296 2401 4096 6561 10000]
    x5: [1 32 243 1024 3125 7776 16807 32768 59049 100000]
save mymatfile.mat -struct data
whos -file mymatfile.mat
  Name      Size            Bytes  Class     Attributes

  x1        1x10               80  double              
  x2        1x10               80  double              
  x3        1x10               80  double              
  x4        1x10               80  double              
  x5        1x10               80  double              
newdata = load('mymatfile.mat')
newdata = struct with fields:
    x1: [1 2 3 4 5 6 7 8 9 10]
    x2: [1 4 9 16 25 36 49 64 81 100]
    x3: [1 8 27 64 125 216 343 512 729 1000]
    x4: [1 16 81 256 625 1296 2401 4096 6561 10000]
    x5: [1 32 243 1024 3125 7776 16807 32768 59049 100000]

Image Analyst 2023-4-28

I guess you didn't check out the FAQ like in my answer because that was shown in the FAQ. Thankfully Steve answered soon or you would have gone longer without a solution. Anyway, the FAQ is still worth looking at because there is lots of interesting other info in there.

Rich006 2023-4-28