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.tur...@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
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