Creating input files for variables

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Cl 2014-10-15

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https://ww2.mathworks.cn/matlabcentral/answers/158753-creating-input-files-for-variables

评论： Stephen23 2023-2-14

I'd like to be able to have an external file which gives all the inputs that a user decides, such as min and max values, directory locations and arrays of periods to use. Is there a way of reading in a file such as:

% Min period
1
% Max period
10
% Directory
'/home/Waves'
% Times
1:5:50

So that I get the equivalent of typing

pmin=1
pmax=10
dir='/home/Waves/'
times=1:5:50

into the code itself?

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Stephen23 2023-2-14

See also:

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

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Answer 1

Stephen23 2014-10-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/158753-creating-input-files-for-variables#answer_155296

编辑：Stephen23 2014-10-15

在 MATLAB Online 中打开

Put this text in a text file named 'temp.txt':

% Min period
1
% Max period
10
% Directory
'/home/Waves'
% Times
1:5:50

Then run this code:

str = fileread('temp.txt');
val = regexp(str,'^%\s*(.+?)\n(.+?)$','tokens','lineanchors');
val = vertcat(val{:});
num = cellfun(@(s)sscanf(s,'%d:'),val(:,2),'UniformOutput',false);
len = cellfun('length',num);
vec = cellfun(@num2cell,num(len>1),'UniformOutput',false);
num(len>1) = cellfun(@(v)colon(v{:}),vec,'UniformOutput',false);
val(len>0,2) = num(len>0);
out = cell2struct(val(:,2),regexprep(val(:,1),' ','_'));

This reads the file as a string, splits the data into names and values, converts the values to numeric (where possible), creates numeric vectors for either of 'X:Y' or 'X:Y:Z', and then merges these numeric values back into the data array.

The final line is optional: it converts the data array (a cell array) to a struct, which would probably be more useful than the cell array.

Note:

The code does not use eval, avoiding any security risk associated with running arbitrary strings from the file.
Extends automatically as many input name + value pairs as you want.
Parameters must be exactly per your example: '% Name of Parameter' followed by a newline, then the parameter value (either a string, a numeric scalar, or colon-format vector).
If you use the struct conversion, the names get used as the struct fieldnames. This limits the choice of characters (read the documentation for more info).