[Rd] [R] help with read.table() function

[Prof Brian Ripley]

On Sun, 29 Jan 2006, Marc Schwartz wrote:

> I would argue against this.
>
> If this were the default, that is requiring user interaction, it would
> break a fair amount of code that I (and I am sure a lot of others have)
> where automation is critical.

I don't see how.  The current default is

> read.table()
Error in read.table() : argument "file" is missing, with no default

so the only change is that the default might do something useful.

Nor do I see the change would help, as the same people would still use a 
character string for 'file' and not omit the argument.  (It seems very 
unlikely that they would read any documentation that suggested things had 
changed.)

The same issue could be made over scan(), where the current default is 
useful.

> A lot of the issues seem to be user errors, file permission errors,
> hidden extensions as is pointed out below and related issues. If there
> is a legitimate bug in R resulting in these issues, then let's patch
> that. However, I don't think that I can recall reproducible situations
> where a bug in R is the root cause of these problems.

Nor I.

Note that file.choose does not protect you against file permission issues 
(actually, on a command-line Unix-alike it does nothing much useful at 
all):

> readLines(file.choose())
Enter file name: errs.txt
Error in file(con, "r") : unable to open connection
In addition: Warning message:
cannot open file 'errs.txt', reason 'Permission denied'

but

> file.show(file.choose())
says

NO FILE errs.txt

which is not a good idea (and I will improve).

So this would really only have any effect on GUI platforms, for people who 
read the documentation.


> Best regards,
>
> Marc Schwartz
>
> On Sun, 2006-01-29 at 12:18 -0500, Duncan Murdoch wrote:
>> (Moved from R-help).
>>
>> This comes up often enough that I'm starting to think most functions
>> that take filename arguments should have file.choose() as the default
>> value.  Then one could do
>>
>> read.table()
>>
>> and have a dialog box pop up in Windows, or some other prompt for a
>> filename in other platforms.  Are there any obviously bad side effects
>> from a change like this?
>>
>> Duncan Murdoch
>>
>> On 1/29/2006 11:51 AM, Peter Dalgaard wrote:
>>> Romain Francois <francoisromain at free.fr> writes:
>>>
>>>> Le 29.01.2006 16:26, oliver wee a écrit :
>>>>
>>>>> hello, I have just started using R for doing a project
>>>>> in time series...
>>>>>
>>>>> unfortunately, I am having trouble using the
>>>>> read.table function for use in reading my data set.
>>>>>
>>>>> This is what I'm getting:
>>>>> I inputted:
>>>>> data <-
>>>>> read.table("D:/Oliver/Professional/Studies/Time Series
>>>>> Analysis/spdc2693.data", header = TRUE)
>>>>>
>>>>> I got:
>>>>> Error in file(file, "r") : unable to open connection
>>>>> In addition: Warning message:
>>>>> cannot open file 'D:/Oliver/Professional/Studies/Time
>>>>> Series Analysis/spdc2693.data', reason 'No such file
>>>>> or directory'
>>>>>
>>>>> as I am just a novice programmer, I really would
>>>>> appreciate help from you guys. Is there a need to
>>>>> setpath in R, like in java or something like that...
>>>>>
>>>>> I am using the windows version btw.
>>>>>
>>>>> I have also tried to put the file in the work
>>>>> directory of R, so that I only typed
>>>>> data <- read.table("spdc2693.data", header = TRUE)
>>>>> Again, it won't work, with the same error message.
>>>>>
>>>>> I would appreciate any help. thanks again.
>>>>>
>>>>>
>>>> Hi, try :
>>>>
>>>> read.table(file.choose(), header=TRUE)
>>>>
>>>> and go to your file.
>>>> Also, you can look a ?setwd, ?getwd
>>>
>>> Right. Or just file.choose() and see what the OS thinks your file is
>>> really called. The most common causes for symptoms like that are
>>>
>>> (A) The file is "spcd2693.data"
>>> (B) There's an extra extension which ever helpful Windows decided to
>>> hide, as in "spdc2693.data.txt".
>>>
>>>
>>
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>
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>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595