Re: [R] write.csv +RMySQL request

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri, 29 Feb 2008 09:16:11 +0000 (GMT)

On Fri, 29 Feb 2008, Tristan Casey wrote:

> Ahh, my apologies I must admit that I don't fully understand
> textConnections fully. I have been reading up on th RODBC package as an
> alternative to RMySQL.
>
> With the file argument in write.csv, are you saying it is possible to
> write the csv formated data directly to a cell in a MySQL database? I am
> unsure what the variable 'con' must consist of.

No, that it is possible to write it to an R character vector.

> Would this need to be a character string that initially connects to the
> database (dbConnect) then pastes the MySQL query? I am unsure how to
> specify where the data is going with the file/connection argument.
>
> Thanks
>
>
>> Date: Fri, 29 Feb 2008 08:44:58 +0000
>> From: ripley_at_stats.ox.ac.uk
>> To: nub_vulcanis_at_hotmail.com
>> CC: jholtman_at_gmail.com; r-help_at_r-project.org
>> Subject: RE: [R] write.csv +RMySQL request
>>
>> On Fri, 29 Feb 2008, Tristan Casey wrote:
>>
>>> Thanks again for your help.
>>>
>>> I am wanting my variable to store a character string exactly as the write.csv function would store as a csv text file;
>>>
>>> IE: My goal is to store a data frame of this construction;
>>>
>>> x1 x2
>>> 1 2
>>> 3 4
>>>
>>> as "X1","X2",1,2,3,4 (the same format as CSV).
>>>
>>> I am aware of the file argument, however that is the problem, storing to
>>> a physical text file and then importing into the SQL database is a very
>>> inefficient way of doing things, especially when I can use RMySQL to
>>> send commands directly to the database.
>>
>> You seem however unaware of text connections. Neither of us said anything
>> about using a 'physical text file', and the documentation for
>> write.csv says
>>
>> file: either a character string naming a file or a connection open
>> for writing. '""' indicates output to the console.
>>
>> A 'text connection; is not a file (physical or otherwise).
>>
>>
>>>
>>> Kind Regards,
>>>
>>> Tristan Casey BPsySci (UQ)
>>> + 4 Festa Court, Capalaba, QLD 4157
>>> H 8/33 Lilly St, Greenslopes, QLD 4120
>>> 0450 033 948
>>>
>>>
>>>
>>>> Date: Fri, 29 Feb 2008 05:12:04 +0000
>>>> From: ripley_at_stats.ox.ac.uk
>>>> To: jholtman_at_gmail.com
>>>> CC: nub_vulcanis_at_hotmail.com; r-help_at_r-project.org
>>>> Subject: Re: [R] write.csv +RMySQL request
>>>>
>>>> On Thu, 28 Feb 2008, jim holtman wrote:
>>>>
>>>>> ?capture.output
>>>>>
>>>>> myoutput <- capture.output(write.csv(...))
>>>>
>>>> It would be better to write directly to a text connection: see the 'file'
>>>> argument to write.csv.
>>>>
>>>>> On Thu, Feb 28, 2008 at 7:34 PM, Tristan Casey <nub_vulcanis_at_hotmail.com> wrote:
>>>>>> Hello,
>>>>>>
>>>>>> I am relatively new to R and learning its ins and outs. As part of a website I am building, I need to read and write csv files directly from an SQL database. Basically I want to convert R variables (dataframes) into CSV format, store them as another R variable (as a properly formatted text string suitable for csv reading) and then send this to one row in a database.
>>>>>>
>>>>>> The SQL part is fine, the problem arises because I cannot capture the output of write.csv! It posts to the terminal when file="" is used, however I also want to store it. Does anyone have any ideas?
>>>>>>
>>>>>> Thanks in advance!
>>>>
>>>> --
>>>> 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
>>>
>>> _________________________________________________________________
>>> Your Future Starts Here. Dream it? Then be it! Find it at www.seek.com.au
>>> http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fninemsn%2Eseek%2Ecom%2Eau%2F%3Ftracking%3Dsk%3Ahet%3Ask%3Anine%3A0%3Ahot%3Atext&_t=764565661&_r=OCT07_endtext_Future&_m=EXT
>>
>> --
>> 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
>
> _________________________________________________________________
> Your Future Starts Here. Dream it? Then be it! Find it at www.seek.com.au
> http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fninemsn%2Eseek%2Ecom%2Eau%2F%3Ftracking%3Dsk%3Ahet%3Ask%3Anine%3A0%3Ahot%3Atext&_t=764565661&_r=OCT07_endtext_Future&_m=EXT

-- 
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

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