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Re: Epilog in ListLogPlot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg81500] Re: Epilog in ListLogPlot
  • From: "D. Grady" <D.C.Grady at gmail.com>
  • Date: Wed, 26 Sep 2007 06:37:15 -0400 (EDT)
  • References: <fd58sd$2i1$1@smc.vnet.net>

The coordinates displayed on the axis of any kind of Log plot
apparently don't correspond to the actual coordinate system used in
the graphic.  If you take a look at the Options of one of the graphics
you generated, the tick marks show that the actual graphics
coordinates run across the logarithms of the y values of your data
points, although the labels on the y-axis don't reflect this.  Two
possible workarounds are to use Scaled coordinates, e.g.

ListLogPlot[X, Epilog -> {Red, Point@Scaled@{.2, .3}}]

or to do something like this:

ListLogPlot[X, Epilog -> {Red, Point@{7, Log[7] }} ]

Hope that helps!

-Daniel Grady

On Sep 23, 3:41 am, Bruce Colletti <vze26... at verizon.net> wrote:
> Re 6.0.1 under WinXP.
>
> Consider the code:
>
> X = {{2, 4}, {9, 5}, {12, 13}};
> ListPlot[X, Epilog -> {Red, Point@{4, 6}}]
> ListLogPlot[X, Epilog -> {Red, Point@{7, 7}}]
>
> Helptext says ListLogPlot has ListPlot's options.
>
> Unlike Plot #1, why doesn't the red dot appear in Plot #2?
>
> Thankx.
>
> Bruce




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