[R] Performing operations only on selected data

[Jeff Newmiller]

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Sent from my phone. Please excuse my brevity.

Marcel Curlin <cemarcel at u.washington.edu> wrote:

>I spent some time on this simple question, also searched the forum,
>eventually hacked my way to an ugly solution for my particular problem
>but I
>would like to improve my coding:
>
>I have data of the form:
>df <- expand.grid(group=c('copper', 'zinc', 'aluminum', 'nickel'),
>condition1=c(1:4))
>
>I would like to add a new data column "condition2", with values equal
>to the
>value of condition1 plus a random number from 0-1 (uniform
>distribution)  if
>the value of condition1 is < 1, or just condition1 if the value of
>condition1 is > 1. More generally, my interest is in manipulating the
>values
>of condition1 if they meet one or more criteria, or keeping the values
>the
>same otherwise. Thanks for any thoughts!
>
> 
>
>
>
>--
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