[R] [FORGED] Re: How create columns for squared values from previous columns?

[C W]

On Sat, Apr 29, 2017 at 10:40 AM, Bert Gunter <bgunter.4567 at gmail.com>
wrote:

> Also:
>
> "I was just a bit frustrated that R wouldn't generate dummy variable
> names on the fly."
>
> That is false. See ?lm  and ?model.matrix
>

I am not sure what you mean. I thought if there is a three level dummy
variable, then it would generate a dummy.1, dummy.2 in lm()


>
> -- Bert
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along
> and sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>
>
> On Sat, Apr 29, 2017 at 1:06 AM, Göran Broström <goran.brostrom at umu.se>
> wrote:
> >
> >
> > On 2017-04-29 06:45, Mike C wrote:
> >>
> >> Thanks Rolf. I was just a bit frustrated that R wouldn't generate
> >> dummy variable names on the fly.
> >>
> >> Also, another question, if I want to put column 5 at column 3,
> >>
> >> dat[, 3:5] <- dat[, c(5,3,4)]
> >>
> >> It does not work, why?
> >
> >
> > It "works", but you need to shuffle the names in the same way:
> >
> > names(dat)[3:5] <- names(dat)[c(5,3,4)]
> >
> > Better(?):
> >
> > perm <- c(1,2,5,3,4)
> > dat <- dat[perm]
> >
> > dat is a list.
> >
> > Göran
> >
> >
> >>
> >> ________________________________ From: Rolf Turner
> >> <r.turner at auckland.ac.nz> Sent: Friday, April 28, 2017 10:48:42 PM
> >> To: C W Cc: r-help Subject: Re: [FORGED] Re: [R] How create columns
> >> for squared values from previous columns?
> >>
> >> On 29/04/17 13:21, C W wrote:
> >>>
> >>> I came up with this solution,
> >>>
> >>>> cbind(dat, dat[, 1:3]^2)
> >>>
> >>> X1         X2         X3         X4          X5          X1 X2
> >>> X3 1  0.72776481 -1.1332612 -1.9857503 0.46189400 -0.09016379
> >>> 0.529641625 1.28428102 3.9432044 2  0.05126592  0.2858707
> >>> 0.9075806 1.27582713 -0.49438507 0.002628194 0.08172203 0.8237026 3
> >>> -0.40430146  0.5457195 -1.1924042 0.15025594  1.99710475
> >>> 0.163459669 0.29780978 1.4218277 4  1.40746971 -1.2279416
> >>> 0.3296075 0.84411774 -0.52371619 1.980970990 1.50784058 0.1086411 5
> >>> -0.53841150  0.4750082 -0.4705148 0.05591914 -0.31503500
> >>> 0.289886944 0.22563275 0.2213842 6  0.90691210  0.7247171
> >>> 0.8244184 0.73328097 -1.05284737 0.822489552 0.52521494 0.6796657
> >>>
> >>> But, you would NOT ONLY get undesired variable names, BUT ALSO
> >>> duplicated names. I suppose I can use paste() to solve that?
> >>>
> >>> Any better ideas?
> >>
> >>
> >> Well, if the names bizzo is your only worry, you could hit the
> >> result with data.frame() *after* cbinding on the squared terms:
> >>
> >> dat <- matrix(rnorm(30),ncol=5) dat <- cbind(dat,dat[,1:3]^2) dat <-
> >> data.frame(dat) names(dat)
> >>
> >> And as you indicate, the names of a data frame are easily adjusted.
> >>
> >> I wouldn't lose sleep over it.
> >>
> >> cheers,
> >>
> >> Rolf Turner
> >>
> >> P.S. You could also do
> >>
> >> names(dat) <- make.unique(names(dat))
> >>
> >> to your original idea, to get rid of the lack of uniqueness.  The
> >> result is probably "undesirable" but.
> >>
> >> R. T.
> >>
> >> -- Technical Editor ANZJS Department of Statistics University of
> >> Auckland Phone: +64-9-373-7599 ext. 88276
> >>
> >> [[alternative HTML version deleted]]
> >>
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> >>
> >
> > ______________________________________________
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> > and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
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