[R] creating a color display matrix

Kartik Pappu kpappu at mednet.ucla.edu
Wed Jul 26 22:30:07 CEST 2006

Hello all,

I am trying to use R to create a colored data matrix.  I have my data 
which (after certain steps of normalization and log transformation) 
gives me a "x by y" matrix of numbers between 0 and -5.  I want to be 
able to create from this matrix of numbers a "x by y" image (box) that 
contains x*y squares and somehow uses the value in the original matrix 
to come up with a color that corresponds to the number.  Hence each box 
will be colored on a scale between 0 and 5.  For example my data could 
look like this:

                 X1.FcH      X2.FcH      X3.FcH     X4.FcH      X5.FcH   
  X6.FcH       X7.FcH
1-AP        0.09667593 -4.66298640 -1.28299697 -4.8739017 -4.95862831 
-5.178603 -4.878524750
2-AP       -4.69186869 -0.08547776 -4.56495440 -4.8348255 -4.80256152 
-5.121531 -4.894347108
3-AP       -1.71380667 -4.52626124 -0.06810053 -4.8703810 -4.65657593 
-5.024595 -4.824712621
4-AP       -4.47968850 -4.48604718 -4.44314403 -0.1569536 -4.86436977 
-4.988196 -4.550416356
5-AP       -4.64616469 -4.53888807 -4.78163386 -4.9162949 -0.01729274 
-5.061663 -0.769960777
6-AP       -4.61047573 -4.60917414 -4.72514817 -5.0084772 -4.87797740 
-0.284934 -1.782745357
7-AP       -4.48157167 -4.61850313 -4.72241281 -4.8694868 -1.66122821 
-3.887898 -0.002522157

How do I make a 7 x 7 box that has 49 squares and each square has a 
color in the RGB spectrum that corresponds to the value.  So for 
example in the matrix above the biggest number which is 0.00966 (at 
position 1 , 1) could be set to RED and the smallest number which is 
5.0084 (at position 6, 5) can be set to BLUE and all the other numbers 
be shades on a scale of Red going to Blue.

I hope this problem makes sense.  I am rather new to R and was 
wondering if there was a function or solution to this problem out 


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