Hi All,
Hi Carl,
I am not sure if this is useful to you, but I followed your conversation
and thought of you when I read this:
for (i in 1:ncol(dataset)) {
if(class(dataset) == "character|numeric|factor|or whatsoever") {
dataset[, i] <- as.factor(dataset[, i])
}
}
Source: Zumel, Nina / Mount, John: Practical Data Science with R, Manning
Publications: Shelter Island, 2014, Chapter 2: Loading data into R, p. 25
This way you can select variables of a certain class only and do
transformations. I found that this approach is not applicable if used with
statistical functions like head(). Transformations worked fine for me.
I found reading the above given source worthwile.
Kind regards
Georg
PS: I am not related to the above given authors. I am just a reader
reporting on - at least to me - a valuable ressource.
Von: Carl Sutton via R-help <r-help at r-project.org>
An: William Dunlap <wdunlap at tibco.com>,
Kopie: "r-help at r-project.org" <r-help at r-project.org>
Datum: 29.04.2016 22:08
Betreff: Re: [R] selecting columns from a data frame or data table
by type, ie, numeric, integer
Gesendet von: "R-help" <r-help-bounces at r-project.org>
Thank you Bill Dunlap. So simple I never tried that approach. Tried
dozens of others though, read manuals till I was getting headaches, and of
course the answer was simple when one is competent. Learning, its a
struggle, but slowly getting there.
Thanks again
Carl Sutton CPA
On Friday, April 29, 2016 10:50 AM, William Dunlap <wdunlap at tibco.com>
wrote:
> dt1[ vapply(dt1, FUN=is.numeric, FUN.VALUE=NA) ] a c1 1 1.12 2
1.0...10 10 0.2
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Fri, Apr 29, 2016 at 9:19 AM, Carl Sutton via R-help
<r-help at r-project.org> wrote:
Good morning RGuru's
I have a data frame of 575 columns. I want to extract only those columns
that are numeric(double) or integer to do some machine learning with. I
have searched the web for a couple of days (off and on) and have not found
anything that shows how to do this. Lots of ways to extract rows, but
not columns. I have attempted to use "(x == y)" indices extraction method
but that threw error that == was for atomic vectors and lists, and I was
doing this on a data frame.
My test code is below
# a technique to get column classes
library(data.table)
a <- 1:10
b <- c("a","b","c","d","e","f","g","h","i","j")
c <- seq(1.1, .2, length = 10)
dt1 <- data.table(a,b,c)
str(dt1)
col.classes <- sapply(dt1, class)
head(col.classes)
dt2 <- subset(dt1, typeof = "double" | "numeric")
str(dt2)
dt2 # not subset
dt2 <- dt1[, list(typeof = "double")]
str(dt2)
class_data <- dt1[,sapply(dt1,is.integer) | sapply(dt1, is.numeric)]
class_data
sum(class_data)
typeof(class_data)
names(class_data)
str(class_data)
Any help is appreciated
Carl Sutton CPA
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______________________________________________
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PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.