subsetting - questions

HI,
This should work:
df[df$X1>=8,][-which(names(df)%in% c("X3","X4","X5"))]
#   X1 X2
#1   8  2
#5  10  1
#8   8  5
#9   9  4
#12  9  5
#13  9 10
#19  9  8
 df[df$X1>=8,][,!names(df)%in%drop_var]
#   X1 X2
#1   8  2
#5  10  1
#8   8  5
#9   9  4
#12  9  5
#13  9 10
#19  9  8
A.K.




----- Original Message -----
From: "Muhuri, Pradip (SAMHSA/CBHSQ)" <Pradip.Muhuri at samhsa.hhs.gov>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc:
Sent: Friday, November 23, 2012 9:55 PM
Subject: [R] subsetting - questions


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

______________________________________________
R-help at r-project.org 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.

Hi Pradip,

It is easier to use subset().  Check ?subset for some examples and pay special attention to the "select" parameter.  By the way, do not call your data "df" as it is already a function.

Best,
Jorge.-


On Sat, Nov 24, 2012 at 1:55 PM, 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

______________________________________________
R-help at r-project.org<mailto:R-help at r-project.org> 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.

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