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Re: Custom ContourLabels in Contour Plots

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  • Subject: [mg110266] Re: Custom ContourLabels in Contour Plots
  • From: "David Park" <djmpark at>
  • Date: Fri, 11 Jun 2010 02:08:26 -0400 (EDT)
  • References: <hm56ku$k47$> <17652030.1276184119509.JavaMail.root@n11>

I don't recall if I ever got an answer to that specific question. There was
a change in the way ContourLabels works in Version 6 (or maybe 7) so you now

ContourLabels -> Automatic for contour labels in tooltips only and
ContourLabels -> True for explicit "printed" contour labels but no tooltips.

But I'm not certain how you get both with plain Mathematica.

With the Presentations package there is a DrawLineLabels routine that will
place explicit contour labels on contour lines (and lines in any 2D plot
that have a function of constant value on the line). So there you could draw
the contour plot with ContourLabels -> Automatic to get tooltips, and then
use DrawLineLabels to explicitly label the contours, or even a selected
subset of contours.

Another quirk of contour labeling is that if you generate a set of contours
by using a Table or Range, say,

Range[-1, 1, 0.2]

you may get a nonzero "zero" value and an ugly label. I suggested to WRI
that since an approximate zero might be a common case they use Chop on label
values, but they thought it is better not to, so you have to do it yourself.

David Park
djmpark at 

From: Istv=E1n Zachar [mailto:zac at]

I am interested in the solution as well! It seems so that this
functionality exists only in theory (the documentation) but not in the

On Feb 25, 8:51 am, "David Park" <djmp... at> wrote:
> I would like to specify custom contour labels in Tooltips for contour
> ContourLabelshas a form {f, g} where f gives an explicit displayed label,
> and g gives a Tooltip for each complete contour. But I can't make this
> work and the Help has no explicit example of this form.
> Here is an example of what I would like to do:
> ContourPlot[Sin[x y] == 1/2, {x, 0, \[Pi]}, {y, 0, \[Pi]},
>  ContourLabels->
>   {Function[{x, y, z}, Text["", {x, y}]],
>    Function[{x, y, z}, Text["My Label"]]}
>  ]  
> No tooltips on the contours. I've tried a number of variations but nothing
> works. Neither does it work on a regular ContourPlot.
> ContourPlot[Sin[x y], {x, 0, \[Pi]}, {y, 0, \[Pi]},
>  Contours -> 5,
>  ContourLabels->
>   {Function[{x, y, z}, Text["", {x, y}]],
>    Function[{x, y, z}, Tooltip["My Label"]]}
>  ]  
> Does anyone know how to do this?
> David Park
> djmp... at

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