[R] predict.lm(...,type="terms") question
David Winsemius
dwinsemius at comcast.net
Sat Sep 1 07:40:33 CEST 2012
On Aug 31, 2012, at 3:48 PM, jjthaden wrote:
> On Aug 30, 2012, at 4:35 PM, David Windemius wrote:
>
>>> David said my newdata data frame 'new' must have a column named
>>> 'area'.
>>> It did. Nonetheless predict.lm throws an error with type = "terms"
>>> and
>>> newdata = new. I see nothing in the predict.lm documentation that
>>> bars this usage. Is there a bug?
>>
>> After correcting the error in your definition of the 'area' vector I
>> get no error from predict.lm().
>
>> David.
>
> What error did you correct?
This was the code you offered:
#Ludbrook's data set S1 (except renaming
#his 'x' as 'concn' and his 'y' as 'area')
S1 <- data.frame(
area = c(2.4,2.6,6.0,6.5,8.9,),
concn = c(1.1,4,5,8.5,8.5))
There's an extra comma in the "area" vector.
>
> The newdata data frames in my examples have been pretty simple, and
> have
> defined the 'area' vector simply, for instance,
> new <- data.frame(area = c(8172, 10220, 11570, 24150))
> new
> # area
> # 1 8172
> # 2 10220
> # 3 11570
> # 4 24150
>
> Is something wrong with this?
I don't really know .... this appears to be a different problem than
you posed earlier. If you would learn to post with context, we might
not be in the position of trying to read your mind.
> Were you able to make predict.lm work with newdata = new and type =
> "terms"?
Yes. I have no trouble doing so.
> x <- rnorm(15); x2=rnorm(15)
> y <- x + x2 +rnorm(15)
> fit <- lm(y ~ x+x2)
> new <- data.frame(x2 = seq(-3.5, 3.5, 0.5) )
> predict(fit, newdata=new,type="terms", terms="x2")
x2
1 -4.9230035
2 -4.1850588
3 -3.4471141
4 -2.7091694
5 -1.9712248
6 -1.2332801
7 -0.4953354
8 0.2426093
9 0.9805539
10 1.7184986
11 2.4564433
12 3.1943880
13 3.9323326
14 4.6702773
15 5.4082220
attr(,"constant")
[1] 0.4501911
>
> -John
>
> Sent from the (NOT) R help mailing list (and NOT) archive at
> Nabble.com.
Hmmm ... Nabble ... definitely part of the problem.
--
David Winsemius, MD
Alameda, CA, USA
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