HI,
I tweaked the code of James a little bit to produce the same result.
> for(i in seq(ncol(df),1))
if(sd(df[,i])==0){
df[,i] <-NULL
}
----- Original Message -----
From: J Toll <[email protected]>
To: Johannes Radinger <[email protected]>
Cc: [email protected]
Sent: Thursday, May 31, 2012 9:52 AM
Subject: Re: [R] Remove columns from dataframe based on their statistics
On Thu, May 31, 2012 at 8:27 AM, Johannes Radinger <[email protected]> wrote:
> Hi,
>
> I have a dataframe and want to remove columns from it
> that are populated with a similar value (for the total
> column) (the variation of that column is 0). Is there an
> easier way than to calculate the statistics and then
> remove them by hand?
>
> A <- runif(100)
> B <- rep(1,100)
> C <- rep(2.42,100)
> D <- runif(100)
> df <- data.frame(A,B,C,D) # if want to conditionally remove column B and C as
> they show no variations
You could try something like:
for (i in seq(ncol(df), 1))
if (length(unique(df[, i])) == 1) {
df[, i] <- NULL
}
or for just numeric values:
for (i in seq(ncol(df), 1))
if (all(mean(df[, i]) == df[, i])) {
df[, i] <- NULL
}
HTH,
James
______________________________________________
[email protected] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
[email protected] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
