Creating input files for variables

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?

[Stephen23]

See also:

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

Answer 1

[Stephen23]

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).

[Stephen23]

Replacing line three with

val = strtrim(vertcat(val{:}));

which will make it immune to trailing whitespace.

[omar ahmed]

what about if my input is decimal ow can I do it. for ex:

%min

5.5

[Katherine Fehr]

You can change the format in the sscan function from decimal to float:

Before:

num = cellfun(@(s)sscanf(s,'%d:'),val(:,2),'UniformOutput',false);

After:

num = cellfun(@(s)sscanf(s,'%f:'),val(:,2),'UniformOutput',false);

More info: https://www.mathworks.com/help/matlab/ref/sscanf.html