MATLAB: Create string of characters from variable name matlab

nan

I want to create string of characters from variable name And use it as a name of an excel file. It's easy to create a single string but I want to write a function that generalizes this situation. For my part: I have a signal that I have to cut into several windows, for each window I have to calculate values (5 values) And in the end I have to store: for each window of a signal, its parameters in a file

Example:

Signal S.

I cut signal S into 3 windows; I need to create 3 excel files:

S_1
S_2
S_3

Proposed solution :

function str = display (signal, i)
  formatSpec = "% s_% d";
  str = sprintf (formatSpec, signal, i)
end
function FeatureExtract (signal, numOfwindows)
for i = 1: numOfwindows
   feature =parameters (signal);
   str = display (signal, i)
end
end

Main program:

FeatureExtract (mysignal)

I want this result: 3 excel files for 3 windows:

Mysignal_1
Mysignal_2
Mysignal_3

Best Answer

You could use inputname:

function FeatureExtract(signal,numOfwindows)
name = inputname(1);
fmt = '%s_%f';
for k = 1:numOfwindows
    ...
    str = sprintf(fmt,name,k);
    ...
end
end

Note that most likely this is a bad idea anyway, because it implies that you are storing meta-data in variable names. Read these to know why putting meta-data into variable names is a bad idea:

https://www.mathworks.com/matlabcentral/answers/225435-save-variable-as-string-from-user-input

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

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Do NOT do this

This would actually be horribly slow, pointlessly complex, obfuscated, and very buggy way to write your code. You would make your code hard to debug, and a pain to work with. Read this to know why:

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

Using indexing would be simple, neat, and very efficient. You should use one array and indexing. Indexing is the solution you should be using, because it is the most efficient way to write MATLAB code, is simple, neat, and very easy to debug. Indexing is explained quite well in the MATLAB introductory tutorials, which are highly recommended for all beginners:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

MATLAB: Convert cellarray with variables to cellarray of the variable names as strings

Hello Konstantinos,

There kind of is, but Cedric is absolutely right. I have very rarely seen variable names as strings to be necessary in a workflow. However, if you'd like to do it, you can define your own function that then calls inputname:

function varNames = getVarNames(varargin)
    varNames = cell(1,nargin);
    for k = 1:nargin
        varNames{k} = inputname(k);
    end
end

This issue with this is the way that you are looking to call it. You say that you first create your cell array:

VarCell = {P_scav, T_exh, P_eng ... etc} ;

At this point, VarCell does not contain any information about which variables were used to create it. It only knows what the data in those variables was, since it now contains a copy of that data. You'll need to call this getVarNames function with each of those input arguments.

VarCellChar = getVarNames(P_scav, T_exh, P_eng ... etc);

at which point you might as well just create the cell array manually. What you could do is make this function output both VarCell and VarCellChar, and just use it as a packaging and naming function though:

function [varCell, varNames] = getVarCellAndNames(varargin)
    varCell = varargin;
    varNames = cell(1,nargin);
    for k = 1:nargin
        varNames{k} = inputname(k);
    end
end

It'll need to be your own function, since inputname only works on function inputs. And it requires the loop, since inputname only takes scalars.

But definitely think hard about if there is another better way to go about getting the result you want.

-Cam

Best Answer

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