ColorFunction help?

• To: mathgroup at smc.vnet.net
• Subject: [mg74888] ColorFunction help?
• From: AES <siegman at stanford.edu>
• Date: Tue, 10 Apr 2007 05:15:22 -0400 (EDT)
• Organization: Stanford University

```Some time back I asked about creating what a respondent later called
"White to Color" color functions for contour and density plots, and
after some further experimentation I've found that if I define

k1=xx;  k2=yy;  k3=zz;
myPlotColor[i_] = RBGColor[1 - k1 i, 1 - k2 i, 1 - k3 i]

with k1, k2, k3 each set equal to either 0 or 1, and then use

ColorFunction->myPlotColor

in the plot command, I get just the results I want.  For example if I
execute the seven lines (either in a single cell or as separate cells)

k1 = 0; k2 = 1; k3 = 1;

red[i_] = RGBColor[1 - k1 i, 1 - k2 i, 1 - k3 i];

gCP = ContourPlot[(x + y)/2, {x, 0, 1}, {y, 0, 1},
ColorFunction -> red];

k1 = 1; k2 = 0; k3 = 1;

green[i_] = RGBColor[1 - k1 i, 1 - k2 i, 1 - k3 i];

gDP = DensityPlot[(x + y)/2, {x, 0, 1}, {y, 0, 1},
ColorFunction -> green];

Show[GraphicsArray[{{gCP, gDP}}]];

I get the beautiful red ContourPlot  gCP that I want from lines 1 thru
3; the beautiful green DensityPlot  gDP  that I want from lines 4 thru
6; and then the two of them together from line 7.

What puzzles me, however, is that if I replace the string "green" by
"red" in lines 5 and 6 above, the individual plots CP and DP from lines
1 thbru 6 still come out red and green as before --- but the two
graphics produced by the Show[ ] command in line 7 now both come out
green.

The DP resulting from line 6 obviously knew it was supposed to be green
when it was first rendered, even though its ColorFunction was
confusingly named "red", because red[i_] had been redefined using k
values appropriate to green in line 5.  How come it forgets all about
this when Show time comes around?

[Email cc of replies welcomed]

come out green**.

```

• Prev by Date: Re: Question
• Next by Date: Re: question
• Previous by thread: Re: reliability function drawing