ar notation to issue an error when referring to a non-existent
> variable inside the data frame?
>
> Thank you very much.
>
> Paulo Barata
>
> -----
>
>
> ------ Original Message ---
> From: "Frans Marcelissen"
> To: &qu
Hi,
On Tue, Jul 17, 2012 at 10:40 AM, Paulo Barata
wrote:
>
> Dear Frans and Peter,
>
> Yes, the notation df[,'var'] is able to catch a non-existent
> variable var inside a data frame df. But the notation df$var
> isn't.
>
> So we have this situation, where two different notations, which
> (as fa
---
-- Original Message ---
From: "Frans Marcelissen"
To: "'Paulo Barata'" ,
Sent: Mon, 16 Jul 2012 14:25:21 +0200
Subject: RE: [R] variable (column) in a data frame
> Hoi Pauli,
> There is a difference between two ways of accessing co
Hoi Pauli,
There is a difference between two ways of accessing columns in a matrex:
> df$aaa
NULL
> df["AAA"]
Error in `[.data.frame`(df, "AAA") : undefined columns selected
So df["AAA"] or df[,"AAA"] gives the error message you expect.
---
Frans
-Oorspronkelijk bericht-
V
iginal Message ---
From: Peter Ehlers
To: Paulo Barata
Cc: "r-help@r-project.org", peter dalgaard
Sent: Sun, 15 Jul 2012 09:29:11 -0700
Subject: Re: [R] variable (column) in a data frame
On 2012-07-15 08:41, Paulo Barata wrote:
Dr. Dalgaard,
Thank you. But pre-checking with
Hi,
I guess you can try this:
#You will get the same result here:
df$aaa==2
logical(0)
!df$aaa==2
logical(0)
#But it is different for the variable present in the dataframe
df$a==4
[1] FALSE FALSE FALSE
!df$a==4
[1] TRUE TRUE TRUE
identical(df$aaa==2,!df$aaa==2)
[1] TRUE
identical(df$a==4,!
Paulo Barata-3 wrote
>
> Dr. Dalgaard,
>
> Thank you. You are right, with() is able to catch
> spelling errors in the name of variables inside a data frame.
>
> But couldn't some error or warning be included in R when referring
> to a non-existent variable inside a data frame with the df$var
>
nt: Sun, 15 Jul 2012 18:14:22 +0200
Subject: Re: [R] variable (column) in a data frame
> On Jul 15, 2012, at 17:41 , Paulo Barata wrote:
>
> >
> > Dr. Dalgaard,
> >
> > Thank you. But pre-checking with is.null() or using with()
> > doesn't solve the pr
ank you once again.
Paulo Barata
-
-- Original Message ---
From: peter dalgaard
To: "Paulo Barata"
Sent: Sun, 15 Jul 2012 16:47:35 +0200
Subject: Re: [R] variable (column) in a data frame
On Jul 15, 2012, at 16:30 , Paulo Barata wrote:
To the R help
On Jul 15, 2012, at 17:41 , Paulo Barata wrote:
>
> Dr. Dalgaard,
>
> Thank you. But pre-checking with is.null() or using with()
> doesn't solve the problem of catching spelling mistakes
> in the name of a variable inside a data frame, when using
> the df$var notation often in a program.
>
>
o Barata
-
-- Original Message ---
From: peter dalgaard
To: "Paulo Barata"
Sent: Sun, 15 Jul 2012 16:47:35 +0200
Subject: Re: [R] variable (column) in a data frame
> On Jul 15, 2012, at 16:30 , Paulo Barata wrote:
>
> >
> > To the R help li
This seems more or less correct to me.
1> sum(df$a==1)
[1] 1
1> sum(df$a==2)
[1] 1
1> sum(df$aaa==2)
[1] 0
There is no df$aaa so the length is 0 which is what I think you are asking.
What am I missing?
John Kane
Kingston ON Canada
> -Original Message-
> From: paulo.bar...@ensp.fiocruz
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