Error in the anonymous function

Question

shane watson 2024-1-26

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2074611-error-in-the-anonymous-function

评论： shane watson 2024-1-29

Sorry for the basic question, but a help is much appreciated.

I'have following code below and I'm trying to select randomly single value for two or more variables from a vector of 1x24. Self is the vector, here the error appears as follwing. I also find the syntax error, however, I can't see in problem from myside.

S_r = length (Self);...

↑

Error: Incorrect use of '=' operator. To assign a value to a variable, use '='. To compare values for equality, use

'=='.

P_k = @(Self, ny)(...
    S_r = length (Self,);...
    R_p  = randperm(S_r);...
    D_i = R_p(1:ny);...
    C_a(D_i)... 
    );

In addition, I also see syntax errors e.g., invalid syntax at '='.A'(' on line 26 might be missing')' line 26 is the first line.

And on the last line it is parse error at ')': usage might invalid syntax error

I can also attached a simple example of the whole secnario below.

 Define A as a 1x24 vector
A = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, ...
21, 22, 23, 24];
% Define an anonymous function that returns a random subset of n values from A
sample = @(A, n) ( ... % Use @ to define an anonymous function
N = length(A); ... % Get the size of A
P = randperm(N); ... % Generate a random permutation of the indices of A
I = P(1:n); ... % Select the first n indices from the permutation
A(I) ... % Access the corresponding values of A
);
% Define the number of iterations
iterations = 24;
% Loop for each iteration
for i = 1:iterations
% Sample two values from A and assign them to B and C
[B, C] = sample(A, 2);
% Print B and C
fprintf('Iteration %d: B = %d, C = %d\n', i, B, C);
end

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Answer 1

VBBV 2024-1-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2074611-error-in-the-anonymous-function#answer_1397831

编辑：VBBV 2024-1-26

在 MATLAB Online 中打开

% Define A as a 1x24 vector
AA = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, ...
21, 22, 23, 24];
n = 2;  % change the value here
N = length(AA); % Get the size of A
% Define the number of iterations
iterations = 24;
% Loop for each iteration
for i = 1:iterations
    
P = randperm(N); ... % Generate a random permutation of the indices of A
I = P(1:n); ... % Select the first n indices from the permutation
AA(I); % Access the corresponding values of A
% Define an anonymous function that returns a random subset of n values from A
sample = @(A, n) [N P I A]; %... % Use @ to define an anonymous function
fprintf('Iteration %d: \n', i)
% Sample two values from A and assign them to B and C
sample(AA(i), n)
% Print B and C
end
Iteration 1: 
ans = 1×28
    24    20    12     3     8    13    22    17     5     2    10    14    24    18    11     9    15    23    16    19     7     1     6     4    21    20    12     1
Iteration 2: 
ans = 1×28
    24    16    17    10     6    24    20    13     9     1     3    18    21    22    12     4     7    15     2    23     8    11     5    19    14    16    17     2
Iteration 3: 
ans = 1×28
    24     8    10     3     6    13    11    17    19     4    15    12    14    22     9    20    18    21    23    16     7     1     5    24     2     8    10     3
Iteration 4: 
ans = 1×28
    24    15    14    24    10    19    23    21    17    13    12    18    22     1     5     6     4     9    16     3    20     2     8     7    11    15    14     4
Iteration 5: 
ans = 1×28
    24    24     1    23    12     5     8    15     9    17     6    19    21    14    13    16     4    11     2    18    22     3    20    10     7    24     1     5
Iteration 6: 
ans = 1×28
    24    12    13    24     1    11     8    22    10    15     6    19     4     7    20    16     5    21    23    14    17     2     9    18     3    12    13     6
Iteration 7: 
ans = 1×28
    24    13     1     9     6    18    19    17    23    15     8     7    21     2    11    12     3    14    10     5    20    24    22    16     4    13     1     7
Iteration 8: 
ans = 1×28
    24     6     4    14    17     3    10    16    22    20     5    13    12     2    23    18    11    24     8     9    21     7     1    15    19     6     4     8
Iteration 9: 
ans = 1×28
    24     6     9    13    23     5    21     1     2    14    15     7    22    12    16    10    24     3    20    19    17    11    18     8     4     6     9     9
Iteration 10: 
ans = 1×28
    24    12    19     2     4     6     8     3    16    11    14    18    23    17    10    21    15     5    13    22    24    20     7     9     1    12    19    10
Iteration 11: 
ans = 1×28
    24     5     8     7    21     6     2     3    22     4    15    10    13    12    19     9     1    14    23    16    24    20    17    11    18     5     8    11
Iteration 12: 
ans = 1×28
    24    12     5    21     6    24     9     7     1    11    19    22    10     2    16    14     3    13    18    15     8    23     4    17    20    12     5    12
Iteration 13: 
ans = 1×28
    24    18    16    19    11     3    14    20    24     9    17    22     7     5     8     4    12    15     6     1    10    23     2    21    13    18    16    13
Iteration 14: 
ans = 1×28
    24     6     5    11     8     3    22    17    23    24     2    13    14    16    15     9    20     7    19    18     4    10    21     1    12     6     5    14
Iteration 15: 
ans = 1×28
    24    23    24     2     1    21    12    13    19    20    14     8    22    18     4     3     6    10    16     9     5    15    11    17     7    23    24    15
Iteration 16: 
ans = 1×28
    24     8    18    23    21     1    22    20     3    10    15    11     4     6     5    17     7    13    14    19    12     9    16     2    24     8    18    16
Iteration 17: 
ans = 1×28
    24     7    17     2    12    24    23    13     4     3    19    15    21    14    22    16    20     1     5    11    18     6     8    10     9     7    17    17
Iteration 18: 
ans = 1×28
    24    18    10     5    24    15    12    19    11    16    22     8     6    14    13     4     7     1     2    21     9     3    23    17    20    18    10    18
Iteration 19: 
ans = 1×28
    24    11     5    23    12    15    16     3     7    10    22     9    19     6    20    24    14    13    17     8    18     1    21     4     2    11     5    19
Iteration 20: 
ans = 1×28
    24    19    21    14    12    13    20    10    15    24     6    11     1    17     8     2    18    16     4     7    22    23     5     3     9    19    21    20
Iteration 21: 
ans = 1×28
    24    12     4     1    19     2    17    10    22    23    11     6    16     5    21    13     9     7     3    18    14    24     8    15    20    12     4    21
Iteration 22: 
ans = 1×28
    24    23    11    16     8    19    24    22     2    14     6    10     1     5     9     4    15    17    13     3    20    18    12    21     7    23    11    22
Iteration 23: 
ans = 1×28
    24     5     8    19    18    23    24     1    21     3     9    16     7    12    17    15    14     2    20    10    22    13     6     4    11     5     8    23
Iteration 24: 
ans = 1×28
    24    10     8    15    17    23    16    20    19    18     7     2     1     3    14     4    11     5     9    12    24     6    21    13    22    10     8    24

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VBBV 2024-1-26

' ( ' and ' ) ' are parenthesis used for named function definitions. However, for anonymous function definitons they may not be needed.

shane watson 2024-1-29

@VBBV, Thanks for your response, a bit late to respond you, however, I'm wondering that why matrix size increased from 1x24? And you also, you didn't assign values to B and C. I already accepted your answer, however, could you please respond to me. thanks in advanced

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