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

• To: mathgroup at smc.vnet.net
• Subject: [mg90154] Re: [mg90127] Controling the color of line segments in a Log plot
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Tue, 1 Jul 2008 06:57:18 -0400 (EDT)

You can use ColorFunction but you still lose some of the original Ticks

xy = Table[{n, 10^n}, {n, 10}];

ListLogPlot[xy, Joined -> True]

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

Bob Hanlon

---- Donald DuBois <donabc at comcast.net> wrote:
> I would like to control the color of line segments in a Log plot. I have three Questions (A,B,C) regarding this problem.
>
> A simple example:  I start with the data yValues = Table[10^n, {n,10}] - which should also be the Y-axis tick values - and use ListLogPlot to graph it.
>
> yValues = Table[10^n, {n, 10}]
> xy = Transpose[{Range[Length[yValues]], yValues}]
> ListLogPlot[xy, Joined -> True]
>
>
> Question A . Does anyone find it peculiar that ListLogPlot seems to be taking
> Log to base 10 as a default as in the above plot when Log by itself defaults to base E?  This is FINE for me, as I want it to be to the base 10. But still,
> does anyone know why this is so or am I misconstruing something?
>
>
> Question B.
> I would like to change the color to Red of the line segment with X values going from
> 3 to 6. (In general, I would like to change the segment color to Red for any number of segments of the same Log plot.) Is there a way to do this at the  ListLogPlot level (i.e.giving directives directly to ListLogPlot)?
> That would be the simplest solution.
>
> I can change the color of this part of the graph by going down to the Graphics element level using Line as in the following, but this is tedious.
>
> logY = Map[N[ Log[10, #]] &, yValues]
> xyLog = Transpose[{Range[Length[logY]], logY}]
> l2 = Graphics[{Red, Thick, Line[Take[xyLog, {3, 6}]]}];
> l1 =  Graphics[{Line[Take[xyLog, {1, 3}]]}];
> l3 =   Graphics[{Line[Take[xyLog, {6, 10}]]}];
> Show[l1, l2, l3, Axes -> True, AxesOrigin -> {0, 0}]
>
> Question C.  The above graph loses the original Y axis tick values which are contained in the yValues list defined above.  Is there any way to solve this?  I want the graph to look like the first graph above  with the same Y tick values (using ListLogPlot) except the Line segment with X values from 3 to 6 should be Red.
>