Chuck Cleland wrote:
> On 2/23/2008 9:13 AM, Robert Walters wrote:
>> Chuck Cleland wrote:
Chuck,
For the record, I might add that that the following two variants for
subsetting worked equally well:
fit1 <- lm(pore.pct ~ Db, subset(data.b, porosity == "macro "))
fit1 <- lm(pore.pct ~ Db, data.
Greg Snow wrote:
> Look carefully at the output and commands below.
>
> The first level of porosity is "macro " (notice the space at the
> end) but you are asking for "macro" (without the space). Computers are
> very literal, so "macro " is not equal to "macro". T
Greg and Chuck,
Thanks for
t;porosity.somethingelseafterthemainname", but the subset command
is only looking for something named "porosity" and will not match the others).
Hope this helps,
From: [EMAIL PROTECTED] on behalf of Robert Walters
Sent: Sat 2/23/2008 7:13 AM
To
Chuck Cleland wrote:
> On 2/23/2008 6:09 AM, Chuck Cleland wrote:
>> On 2/22/2008 8:01 PM, Robert Walters wrote:
Chuck,
Thanks for the pointers on subset(). When I submit the two variants you
suggested, below:
> fit1 <- lm(y ~ x, subset(data.b, porosity == "macro"))
Error in eval(expr, envir, e
Erin Hodgess wrote:
> Hi Robert!
>
> Could you please check
> str(data.b)
>
> and see what you have for porosity? It needs to be a factor
>
> Thanks,
> Erin
>
>
Erin,
Yes, porosity is a factor. See output below.
> str(data.b)
'data.frame': 96 obs. of 7 variables:
$ system : Factor w/
On 2/23/2008 6:09 AM, Chuck Cleland wrote:
> On 2/22/2008 8:01 PM, Robert Walters wrote:
>> R folks,
>> As an R novice, I struggle with the mystery of subsetting. Textbook
>> and online examples of this seem quite straightforward yet I cannot
>> get my mind around it. For practice, I'm using the
On 2/22/2008 8:01 PM, Robert Walters wrote:
> R folks,
> As an R novice, I struggle with the mystery of subsetting. Textbook and
> online examples of this seem quite straightforward yet I cannot get my
> mind around it. For practice, I'm using the code in MASS Ch. 6,
> "whiteside data" to analyz
R folks,
As an R novice, I struggle with the mystery of subsetting. Textbook and
online examples of this seem quite straightforward yet I cannot get my
mind around it. For practice, I'm using the code in MASS Ch. 6,
"whiteside data" to analyze a different data set with similar variables
and str
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