subsetting - questions
Hello Peter,
1. -c("X3", "X4", "X5")
For the above variables, class is integer.
Arun has suggested the following:
df[df$X1>=8,][-which(names(df)%in% c("X3","X4","X5"))]
2. df[df$X1>=8,] [, !names(df) %in% drop_var]
I agree - Arun has also suggested the same.
Thanks and regards,
Pradip
From: Peter Ehlers [ehlers at ucalgary.ca]
Sent: Friday, November 23, 2012 10:47 PM
To: Muhuri, Pradip (SAMHSA/CBHSQ)
Cc: r-help at r-project.org
Subject: Re: [R] subsetting - questions
Sent: Friday, November 23, 2012 10:47 PM
To: Muhuri, Pradip (SAMHSA/CBHSQ)
Cc: r-help at r-project.org
Subject: Re: [R] subsetting - questions
On 2012-11-23 18:55, Muhuri, Pradip (SAMHSA/CBHSQ) wrote:
>
> Hello,
>
> I have two very basic questions (console attached):
>
> 1) What am I getting an error message for # 5 and # 7 ?
> 2) How to fix the code?
>
> I would appreciate receiving your help.
>
> Thanks,
>
> Pradip Muhuri
>
>
>
> ###### Reproducible Example #####
>
> N <- 100
> set.seed(13)
> df<-data.frame(matrix(sample(c(1:10),N, replace=TRUE),ncol=5))
>
> keep_var <- c("X1", "X2")
> drop_var <- c("X3", "X4", "X5")
>
>
> df[df$X1>=8,] [,1:2] #1
> df[df$X1>=8,] [,-c(3,4,5)] #2
> df[df$X1>=8,] [,c(-3,-4,-5)] #3
> df[df$X1>=8,] [,c("X1", "X2")] #4
> df[df$X1>=8,] [,-c("X3", "X4", "X5")] #5 DOES NOT WORK
> df[df$X1>=8,] [,keep_var] #6
> df[df$X1>=8,] [, !drop_var] #7 DOES NOT WORK
To see what's wrong, just print the problematic part:
-c("X3", "X4", "X5")
You can't negate a character vector; you have to have a numeric vector.
And
!drop_var
doesn't work because you need something that evaluates to a logical
value if you want to "!" it.
This will do it:
df[df$X1>=8,] [, !names(df) %in% drop_var]
Or use the subset() function, as Jorge suggests.
Peter Ehlers