[BioC] trasnforming log base 2 values into decimal values

[James W. MacDonald]

D.Enrique ESCOBAR ESPINOZA wrote:
> hi,
> I am working with an expression matrix,
> I think I will use ratios for analysis of 2 conditions,
> does anyone know how to change values in a matrix.
> 
> if I have 3 in log2 => 2^3=8 in decimal,
> how I do that in R for an entire vector or matrix?

Did you try the obvious?

 > x <- 1:5
 > 2^x
[1]  2  4  8 16 32
 > y <- matrix(rep(1:5, 5), ncol=5)
 > 2^y
      [,1] [,2] [,3] [,4] [,5]
[1,]    2    2    2    2    2
[2,]    4    4    4    4    4
[3,]    8    8    8    8    8
[4,]   16   16   16   16   16
[5,]   32   32   32   32   32

Best,

Jim


> Thanks
> 
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-- 
James W. MacDonald, M.S.
Biostatistician
Affymetrix and cDNA Microarray Core
University of Michigan Cancer Center
1500 E. Medical Center Drive
7410 CCGC
Ann Arbor MI 48109
734-647-5623


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