Hello,

I'm glad that it worked.
Two things:

1. Please, click reply all to keep this threaded.
2. The question should have belonged to r-h...@r-project.org, not to r-devel@r-project.org.

Rui Barradas

Às 07:10 de 17/03/20, Moshe Olshansky escreveu:
It works, thank you!

On Tuesday, 17 March 2020, 5:47:05 pm AEDT, Rui Barradas <ruipbarra...@sapo.pt> wrote:


Hello,

The problem seems to be that A is a matrix. The following solves the error.

# create A and b as in your code then run
A <- as.data.frame(A)
df1 <- cbind(A, b)
reg <- lm(b ~ ., df1)

# etc


Hope this helps,

Rui Barradas

Às 04:36 de 17/03/20, Moshe Olshansky via R-devel escreveu:
 > Hello,
 > Below is my code:
 >> A <- matrix(rnorm(10*3),ncol=3)
 >> b <- runif(10)
 >> reg <- lm(b ~ A)
 >> A1 <- matrix(rnorm(5*3),ncol=3)
 >> A1 <- as.data.frame(A1)
 >> b1 <- predict(reg,A1)
 > Warning message:
 > 'newdata' had 5 rows but variables found have 10 rows
 >
>    And instead of being an array of length 5, b1 is of length 10 and is identical to reg$fitted.values
 > I think that it should not be like this.
> Let me note that for lm I do not care about this as much since I can use reg$coefficients, but unfortunately this behaviour is "inherited" by other methods. When I am trying to fit a regression tree, predicting from the object without using 'predict' method is less trivial.
 > Thank you,Moshe.
 > P.S. just in case:> sessionInfo()
 > R version 3.6.2 (2019-12-12)
 > Platform: x86_64-pc-linux-gnu (64-bit)
 > Running under: Linux Mint 19.1
 >
 > Matrix products: default
 > BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.7.1
 > LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.7.1
 >
 > locale:
 > [1] C
 >
 > attached base packages:
 > [1] stats     graphics  grDevices utils     datasets  methods   base
 >
 > loaded via a namespace (and not attached):
 > [1] compiler_3.6.2 tools_3.6.2

 >
 >
 >
 >
 >
 >     [[alternative HTML version deleted]]
 >
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 >

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