Hi, I have a matrix in which my columns are my samples and rows my genes. How I can write a function in R so that each value in this matrix be e^value?? I mean anti natural log of the values inside this matrix. Whatever I am googling I failed especially I am not allowed to ask in stack overflow.
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written
by
Za
2 answers
Wait, on which scale are your values currently? Already logged or not?
You literally just want e^value? Then, that's just
2.71828182846^datamatrix
...or
exp(datamatrix)
If they are the natural logged values, then, yes, just use either of:
2.71828182846^datamatrix
exp(datamatrix)
Then, they will be back on the scale they were before natural log transformation, i.e., anti natural log.
Testing:
2.71828182846^log(2)
[1] 2
exp(log(2))
[1] 2
Reversing a log is called exponentiation. To apply a function to every cell of a matrix, you can use the apply() function specifying both rows and columns in the margin parameter. The example below reverses the log2 transformation used for example in microarray data:
exponentiated.data <- apply(log.data, 1:2, function(x) { 2^x})
Umm, 2^log.data is a bit simpler. Of course since OP wants the natural log exp(log.data) would be the equivalent.
Yes / Sim / Sea / Oui / Si
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