       Re: Controling the color of line segments in a Log plot

• To: mathgroup at smc.vnet.net
• Subject: [mg90209] Re: Controling the color of line segments in a Log plot
• From: Donald DuBois <donabc at comcast.net>
• Date: Wed, 2 Jul 2008 05:31:15 -0400 (EDT)

```David Park wrote:

"One might have hoped that the following construction would work:

ListLogPlot[xy, Joined -> True,
ColorFunction -> Function[{x, y}, If[3 <= x <= 6, Red, Black]]]

But it doesn't. Perhaps someone will know how to make that approach work."

It appears that, following Bob Hanlon's approach,
ColorFunctionScaling -> False is needed  as in:

yValues = Table[10^n, {n, 10}]
xy = Transpose[{Range[Length[yValues]], yValues}]
ListLogPlot[xy, Joined -> True,
ColorFunction -> Function[{x, y}, If[3 <= x <= 6, Red, Black]],
ColorFunctionScaling -> False]

ColorFuncttionScaling is, by default, set to True which assumes the x values are in the Range [0,1]. See
Documention Center for more details.  The above approach can be expanded to include multiple ranges of x values:

ListLogPlot[xy, Joined -> True,
ColorFunction ->
Function[{x, y}, If[3 <= x <= 6 || 8 <= x <= 8
|| 1 <= x <= 1 , Red, Blue]],
ColorFunctionScaling -> False]

I am still evaluating which is the best way to go to get the correct tick marks etc.  I appreciate all the responses.  Thank you.

```

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