R help - Oct 2017 - read.table(..., header == FALSE, colClasses = <vector with names attribute>)

Hello

I noticed that starting with R version 3.3.0 onward, this generates a 
warning:

 ?? > txt <- c("a", "3.14")
 ?? > read.table(file = textConnection(txt), header = FALSE, colClasses 
= c(x = "character", y = "numeric"))

the warning is "not all columns named in 'colClasses' exist"
and I guess
the change was made in response to this?

 ?? https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=16478

Regardless, I am wondering whether this is desirable, that as a result 
of the change, the code has become stricter about the presence of a 
(formerly) harmless names attribute. Or am I missing something?

Regards

Ben

You are constructing the equivalent of a two-line data file, and complaining
that it is not treating it like it was one line. If it did used to accept this
silently [skeptical] then I for one am glad it produces a warning now.
-- 
Sent from my phone. Please excuse my brevity.

On October 23, 2017 2:53:21 PM PDT, Benjamin Tyner <btyner at gmail.com>
wrote:
>Hello
>
>I noticed that starting with R version 3.3.0 onward, this generates a 
>warning:
>
> ?? > txt <- c("a", "3.14")
>?? > read.table(file = textConnection(txt), header = FALSE, colClasses 
>= c(x = "character", y = "numeric"))
>
>the warning is "not all columns named in 'colClasses'
exist" and I
>guess 
>the change was made in response to this?
>
> ?? https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=16478
>
>Regardless, I am wondering whether this is desirable, that as a result 
>of the change, the code has become stricter about the presence of a 
>(formerly) harmless names attribute. Or am I missing something?
>
>Regards
>
>Ben
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

Jeff,

Thank you for your reply. The intent was to construct a minimum 
reproducible example. The same warning occurs when the 'file' argument 
points to a file on disk with a million lines. But you are correct, my 
example was slightly malformed and in fact gives an error under R 
version 3.2.2. Please allow me to try again; in older versions of R,

 ?? > read.table(file = textConnection("a\t3.14"), header = FALSE, 
colClasses = c(x = "character", y = "numeric"),
sep="\t")
 ? ?? V1?? V2
 ?? 1? a 3.14

(with no warning). As of version 3.3.0,

 ?? > read.table(file = textConnection("a\t3.14"), header = FALSE, 
colClasses = c(x = "character", y = "numeric"),
sep="\t")
 ? ?? V1?? V2
 ?? 1? a 3.14
 ?? Warning message:
 ?? In read.table(file = textConnection("a\t3.14"), header = FALSE,? :
 ? ?? not all columns named in 'colClasses' exist

My intent was not to complain but rather to learn more about best 
practices regarding the names attribute.

Regards

Ben



On 10/23/2017 08:51 PM, Jeff Newmiller wrote:
> You are constructing the equivalent of a two-line data file, and
complaining that it is not treating it like it was one line. If it did used to
accept this silently [skeptical] then I for one am glad it produces a warning
now.