如何在不打印的情况下在Matlab循环中监视变量？

Question

我正在运行一个循环,其中计算变量.能够看到这些变量的当前值是有用的.打印它们没有用,因为循环的其他部分正在打印大量文本.此外,在Workspace选项卡上,值不会显示,直到循环结束.

有没有办法监控这些变量,通过将它们打印到窗口中？

Answer 1

您可以使用text对象创建一个图形,并'string'根据所需的变量更新其属性:

h = text(.5, .5, ''); %// create text object
for n = 1:1000
    v = n^2; %// loop computations here. Variable `v` is to be displayed
    set(h, 'string', ['Value: ' num2str(v)]);
    drawnow %// you may need this for immediate updating
end

为了获得更高的速度,您可以只更新每次S迭代:

h = text(.5, .5, ''); %// create text object
S = 10; %// update period
for n = 1:1000
    v = n^2; %// loop computations here. Variable `v` is to be displayed
    if ~mod(n,S) %// update only at iterations S, 2*S, 3*S, ...
        set(h, 'string', ['Value: ' num2str(v)]);
        drawnow %// you may need this for immediate updating
    end
end

或者drawnow('limitrate')按照@Edric的说明使用:

h = text(.5, .5, ''); %// create text object
for n = 1:1000
    v = n^2; %// loop computations here. Variable `v` is to be displayed
    set(h, 'string', ['Value: ' num2str(v)]);
    drawnow('limitrate')
end