# Why the V parameter in matplotlib.axes.Axes.contour must be increasing?

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## Why the V parameter in matplotlib.axes.Axes.contour must be increasing?

 Hi,https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.contour.html says the contour function accept a vector parameter V which must be in increasing value. But the contour function in MATLAB does not have this restriction.I understand the underlining implementation of these two functions could be very different. I want to understand what is the purpose of this restriction, and if it possible to create a contour image the same as MATLAB does by using contour with V = [0 0]?Regards,David _______________________________________________ Matplotlib-users mailing list [hidden email] https://mail.python.org/mailman/listinfo/matplotlib-users
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## Re: Why the V parameter in matplotlib.axes.Axes.contour must be increasing?

 Probably because nobody noticed that discrepancy before. I'd imagine it would be fairly simple to apply a sort to the list of values within the function itself. The underlying contouring implementation assumes a monotonically increasing set of contour levels, and I would imagine that MATLAB's version does too -- just that they sort the contour levels for you.At the moment, I don't see any reason why we couldn't do that, too.Cheers!Ben RootOn Wed, Aug 16, 2017 at 8:33 AM, Xi Shen wrote:Hi,https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.contour.html says the contour function accept a vector parameter V which must be in increasing value. But the contour function in MATLAB does not have this restriction.I understand the underlining implementation of these two functions could be very different. I want to understand what is the purpose of this restriction, and if it possible to create a contour image the same as MATLAB does by using contour with V = [0 0]?Regards,David _______________________________________________ Matplotlib-users mailing list [hidden email] https://mail.python.org/mailman/listinfo/matplotlib-users _______________________________________________ Matplotlib-users mailing list [hidden email] https://mail.python.org/mailman/listinfo/matplotlib-users
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## Re: Why the V parameter in matplotlib.axes.Axes.contour must be increasing?

 In reply to this post by Xi Shen Hi David, I’ve definitely run into this, to my annoyance. Do you think you can open an issue on GitHub? If you don’t want to, I’m happy to do it. With respect to one contour at zero, its easier than Matlab: ax.contour(X, np.array([0.])) works for me… Cheers, On 16 Aug 2017, at 5:33, Xi Shen wrote: Hi,https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.contour.html says the contour function accept a vector parameter V which must be in increasing value. But the contour function in MATLAB does not have this restriction.I understand the underlining implementation of these two functions could be very different. I want to understand what is the purpose of this restriction, and if it possible to create a contour image the same as MATLAB does by using contour with V = [0 0]?Regards,David _______________________________________________ Matplotlib-users mailing list [hidden email] https://mail.python.org/mailman/listinfo/matplotlib-users _______________________________________________ Matplotlib-users mailing list [hidden email] https://mail.python.org/mailman/listinfo/matplotlib-users