R help - Jul 2010 - log transformation

Hi,

I am reading an article in which, first, some given "p-results" are
obtained, and, second, these are afterwards transformed and expressed as the
"NEGATIVE base-10 logarithm of the p-value". 

My question is if anyone could indicate how is such transformation achieved
with R and how are they expressed exponentially, as in for example 1.8E-18.

Thank you!
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jarry <jarryjarry58 <at> hotmail.com> writes:
> 
> 
> Hi,
> 
> I am reading an article in which, first, some given "p-results"
are
> obtained, and, second, these are afterwards transformed and expressed as
the
> "NEGATIVE base-10 logarithm of the p-value". 
> 
> My question is if anyone could indicate how is such transformation achieved
> with R and how are they expressed exponentially, as in for example 1.8E-18.
> 
  ?? presumably 

 -log10(pvalue)

  ??

  so a p-value of 1.8e-18 (i.e., 1.8 times 10^-18) would correspond to
a value of 17.74