MATLAB: Get the numeric value of a variable using sprintf

numeric valuesprintf

Hi,

How can I get the numerical value of a variable doing something like this:

num_1=2;
num_2=5;
num=3=9;
random_num=randsample([1 2 3],1)
Time=sprintf('num_%d',random_num)

Then I get Time=num_X but what I want is to get the numerical value associated to num_X

Any clue on how to do it?

Thank you very much.

Best Answer

The only way I can think to do it is to use the ‘evil eval’:

Time - num_2
Time = eval(Time)
Time =
     5

But as Walter wrote, it’s best to avoid it altogether.

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MATLAB: Counting duplicate values in a column

I am not certain how robust this will be for a different problem,. however it works here with the example posted:

A = { 2        'a'
      3        'a'
      1        'a'
      2        'b'
      6        'a'
      1        'c'
      7        'c'};
[UAs,~,ic] = unique(A(:,2));                                    % Unique Indices Of ‘Num_2’
Tallyc = accumarray(ic, 1, [], @(x){cumsum(x)});                % Cumulative Sums Of Indices In ‘Num_2’
Idxc = accumarray(ic, (1:size(A,1)).', [], @(x){x});            % Their Respective Indices
Tallyv = cell2mat(Tallyc);                                      % Convert From Cell Arrays To Vectors

Idxv = cell2mat(Idxc);                                          % Convert From Cell Arrays To Vectors
T1 = cell2table(A);                                             % Create Table For ‘A’
T1 = [T1, table(Tallyv(Idxv))];                                 % Create Table For ‘Column_3’
T1.Properties.VariableNames = {'Num','Num_2','Column_3'}        % Result

producing:

T1 =
  7×3 table
    Num    Num_2    Column_3
    ___    _____    ________
     2     {'a'}       1    
     3     {'a'}       2    
     1     {'a'}       3    
     2     {'b'}       1    
     6     {'a'}       4    
     1     {'c'}       1    
     7     {'c'}       2

MATLAB: How to write code for hankle and toeplitz matrix

My apologies! I was not thinking clearly when I wrote the nonsensical A.^(0:9). The following should produce the desired two arrays.

   M = 6;  % A is M x M, B is M x 1, C is 1 x M
   N = 10;
   F = zeros(N+1,M);
   F(1,:) = C;
   for k = 2:N+1
     F(k,:) = F(k-1,:)*A;
   end
   r = F(1:N,:)*B;
   c = [C*B;zeros(M-1,1)];
   phi = toeplitz(r,c);
   F = F(2:N+1,:);

Best Answer

Related Solutions

MATLAB: Counting duplicate values in a column

MATLAB: How to write code for hankle and toeplitz matrix

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