[R] simple problems
Gabor Grothendieck
ggrothendieck at gmail.com
Thu Dec 6 23:40:04 CET 2007
On Dec 6, 2007 3:26 PM, marciarr <marcia.rocha at gmail.com> wrote:
>
> Hello R users,
> I have been looking through Help files and Nabble list for the answers for
> these simple questions, but it seems to be fruitless.
> 1- in a data frame with two columns, x and y, how do I get the corresponding
> value of x to, let's say, the minimum value of the y column (min (data$y)) ?
In the builtin Formaldehyde data frame find the value of carb (first column)
which corresponds to the least value of optden (second column):
with(Formaldehyde, carb[which.min(optden)])
> 2- how do I solve a simple equation? Considering the equation y= exp(-x)^12,
> I would like to find the values of x for, for example, y=0.01, so
> exp(-x)^12=0.01. How do I do that using R?
> I know those a probably very, very simple questions, but for which I do not
> seem to find the answer.
Search between 0 and 1 for the root of the indicated function:
uniroot(function(x) 0.1 - exp(-x)^12, 0:1)
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