accumulate values in aftereach function

Question

dleal 2022-4-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1699505-accumulate-values-in-aftereach-function

评论： dleal 2022-4-20

采纳的回答： Raymond Norris

在 MATLAB Online 中打开

Hi all,

I would like to accumulate values that I collect in real time from a function that runs in the background.

For example

q = parallel.pool.DataQueue;
f1 = AfterEach(q, @afterFunc);
fut1 = parfeval(@genData, 0, q1)
function  genData(q1)
while true
    send(q1, randn)
end
end

Ideally I would be able to accumulate using persistent variable, but I understand persistant variables cannot be used in cunjunction with parfeval:

function afterfunc(x)
persistent y;
if isempty(y); y = []; end;
y = [ y, x];
plot(y); % for example
end

I know I could accumulate the values in the genData(q1) function, but then, after a few thousand iteration, I would be sending a very large vector and it would take longer (then desired) to send

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Answer 1

Raymond Norris 2022-4-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1699505-accumulate-values-in-aftereach-function#answer_946155

在 MATLAB Online 中打开

Persistent variables should work. Try the following

q = parallel.pool.DataQueue;
q.afterEach(@afterFunc);
f = parfeval(@genData, 0, q);
function genData(q)
while true
    send(q, randn)
    pause(1)
end
end
function afterFunc(x)
persistent y
if isempty(y)
    y = [];
end
y = [y, x];
plot(y)
end