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**.