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Re: contour-plot & ascii-art

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23746] Re: [mg23691] contour-plot & ascii-art
  • From: Wolf Hartmut <hwolf at debis.com>
  • Date: Mon, 5 Jun 2000 01:09:40 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

        -----Urspr\174ngliche Nachricht-----
        Von:    Nicola Attico [SMTP:attico at peg2.difi.unipi.it]

        Someone can explain me how to create a
        shaded contour plot together with a bar where the
        various gray-levels have a numerical value
        specified (a sort of thermometer).
        This is a very usual way of specifying the
        ``z-value'' associated with a gray-level.
        I'm sure Mathematica has this feature.

Nicola,

to make up a sample:

f[x_, y_] :=
  With[{a = y Exp[-(y^2 - 1)], b = 1 + Exp[-y^2]/2},
    a With[{x1 = 0.776887 b x},
           2 - ((-0.5 - x1)(0.5 - x1))^2/0.5^4 ] +
          (1 - a) (1 - (b x)^4 ) /; (b x)^2 < 1 && y > 0]

f[x_, y_] := With[{b = 1 + Exp[-y^2]/2}, (1 - (b x)^4 )
                  /; (b x)^2 < 1 ]
f[__] = 0;

p = DensityPlot[f[x, y], {x, -1.3, 1.3}, {y, -2.5, 2},
    ColorFunction -> (GrayLevel[1 - #] &), PlotPoints -> 30,
    DisplayFunction -> Identity]

(* Never mind what f[x,y] is. *)

<< Graphics`Legend`

max = 1`3 + Sqrt[E/2]

ShowLegend[p, {GrayLevel, 6, ToString[max], "0.",
    LegendPosition -> {1.1, -.4}}]

Oh, looking at the subject, sorry, if you prefer the ContourPlot, just
replace p -> ContourGraphics[p] in the preceeding expression.
 

-- Hartmut Wolf




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