MATLAB: How to Create a loop that can find the Max Values of different matrices

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I'm new to MatLab and I want to create an array that contains all the max values of different matrices from my workspace using a while Loop (or any loop).

Best Answer

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

save copy_of_all_variables.mat
copy_of_all_variables = load('copy_of_all_variables.mat');
delete('copy_of_all_variables.mat');
varnames = fieldnames(copy_of_all_variables);
numvars = length(varnames);
max_values = cell(numvars,1);
for K = 1 : numvars
  thisvarname = varnames{K};
  thisvarvalue = copy_of_all_variables.(thisvarname);
  if isnumeric(thisvarvalue) || islogical(thisvarvalue) || ischar(thisvarvalue) || ismethod(thisvarvalue, 'max')
     max_values{K} = max(thisvarvalue);
  end
end

Now max_values is a cell array that contains the maximums of every variable for which "max" makes sense to apply. The corresponding variable names are in varnames.

Related Solutions

MATLAB: Concatenate arrays within a loop,

Easy, given any number of arrays in a cell array C. You could use a loop like this, although it is inefficient because the output array is not preallocated:

C = {[1,2],[3,4],...} % cell array of arrays.
A = C{1};
for k = 2:numel(C)
    A = [A;C{k}];
end

Simpler and more efficient would be to concatenate them all at once, without a loop, e.g.:

A = vertcat(C{:})

Whatever you do, do NOT try to access variable names dynamically in a loop! Read this to know why:

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

Using an array (e.g. a cell array) and indexing is much simpler, neater, much more efficient, less buggy, and easier to debug.

MATLAB: Is there a way to convert all values of NaN to zero over the entire workspace

Try the whos function to get a list of variable names, then use eval to set their nans to zero.

% Sample data
v1 = [0 0 1 1 0 nan 0 1] % Array with nan

v2 =  [0,0,1,1,0,nan,0,1,1,1]  % Array with nan
str = 'abcdef'; % Non numerical array
% Get a list of all variables.
s = whos
for k = 1 : length(s)
  commandLine = sprintf('%s(isnan(%s))=0', s(k).name, s(k).name)
  eval(commandLine)
end
% Let's see if it worked
v1
v2
str  % Hopefully it didn't do anything with this variable.

Best Answer

Related Solutions

MATLAB: Concatenate arrays within a loop,

MATLAB: Is there a way to convert all values of NaN to zero over the entire workspace

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