determine axis limits before plotting..?

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Bradley Stiritz 2012-9-9

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Hi everyone,

I need to determine the y-axis limits "before" rendering my plot, b/c the elements are rendered in a loop, one at a time. xlim() isn't any use in this case. Will I have to reverse-engineer MATLAB's algorithm, or is there another approach?

Thanks, Brad

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Bradley Stiritz 2012-9-9

Hi Oleg,

Thanks for your question. Let me clarify: within the rendering loop, MATLAB is forced to reset the y-axis limits & re-render the whole plot each time a new figure element is drawn which exceeds the current limits. Doing this hundreds of times for a single plot is significantly time-consuming.

Therefore, as I said, I want to determine & set the y-axis limits via ylim() "before" the rendering loop. Does this make sense?

Thanks, Brad

Oleg Komarov 2012-9-9

I think we might help you if you posted the code.

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Answer 1

Jan 2012-9-9

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编辑：Jan 2012-9-10

Yair has explained some tricks to http://undocumentedmatlab.com/blog/plot-performance/. You can set the XLimMode of the current axes to 'fixed' and let Matlab determine the limits at the end only by resetting it to 'auto'.

[EDITED, link fixed, thanks Yair]

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Yair Altman 2012-9-10

编辑：Yair Altman 2012-9-10

The correct link is http://undocumentedmatlab.com/blog/plot-performance/

Also relevant: http://undocumentedmatlab.com/blog/plot-liminclude-properties/

Bradley Stiritz 2012-9-10

Yair, thanks for the very helpful blog postings. Your work is greatly appreciated, as always!

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Answer 2

Image Analyst 2012-9-9

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在 MATLAB Online 中打开

You can save the y and x limits for the current axes at any time by using the ylim and xlim functions:

% Save initial limits.
initial_ylim_values = ylim();
initial_xlim_values = xlim();
% Now plot something that will change the ylimits
plot(x, y); % Some y that will change the y limits.
after_ylim_values = ylim();
after_xlim_values = xlim();