[R] plotting to stdout (while reading from stdin?)

[Gene Selkov]

On Sun, 2 Mar 2008, Gabor Grothendieck wrote:

> You can do this:
>
> Lines <- "A,B
> 1,2
> 3,4"
> DF <- read.csv(textConnection(Lines))
>
> which is slightly simpler than the examples there.

Thank you Gabor,

I made it even simpler by replacing the Lines object with a string 
contstant.

It works perfectly well for me.

Cheers,

--Gene

> On Sun, Mar 2, 2008 at 5:59 PM, Gene Selkov <selkovjr at uchicago.edu> wrote:
>> Hi Dirk,
>>
>> I didn't at first pay attention to your comment about littler, as my
>> original problem of plotting to stdout was solved. But it was just part of
>> the larger problem: I actually need to be piping the data with the code
>> for making the picture in, and getting the picture out without opening any
>> files. This is to be run in a server environment, where the use of temp
>> files is not really acceptable.
>>
>> Having solved half of the problem, I feel cornered again, because I
>> haven't found a nice way of mixing code and data in R.
>>
>> I am aware that this issue was brought up before; I am not sure I like the
>> solutions suggested, because they involve the R language parsing and
>> interpreting for each data row -- if I understand correctly.
>>
>>   http://tolstoy.newcastle.edu.au/R/help/03a/6750.html
>>
>> Are these solutions the best currently available? That thread is almost 5
>> years old now.
>>
>> Let me give you an example of what I would like to be possible:
>>
>> In postgres, I can read this from stdin:
>>
>>    CREATE TABLE remark (
>>      "case" smallint,
>>      text text
>>    );
>>
>>    COPY remark ("case", text) FROM stdin;
>>    877     lymph node biopsy
>>    909     Unresectable mass in the body of the pancreas
>>    \.
>>
>>    ... more SQL ....
>>
>> It allows the "code" and "input" chunks to be mixed, because the
>> input for stdin is always terminated by a special token, '\.', and so the
>> parser can skip the data chunks without interpreting them.
>>
>> Almost similarly, perl has the __DATA__ token, that allows a portion of
>> text within a program to be treated as stdin.
>>
>> I wonder whether anything like this is possible in R or littler.
>>
>>
>> Thanks,
>>
>> --Gene
>>
>>
>> On Fri, 7 Sep 2007, Dirk Eddelbuettel wrote:
>>
>>> On Fri, Sep 07, 2007 at 02:27:00PM -0400, Duncan Murdoch wrote:
>>>> On 9/7/2007 2:15 PM, Gene Selkov wrote:
>>>>> Thanks a ton, Duncan!
>>>>>
>>>>> So I have verified that this line works:
>>>>>
>>>>>    echo "postscript(file=\"\", command=\"cat\"); plot(0)" | r --vanilla --slave
>>>>>
>>>>> Wonderful! (albeit a little unobvious)
>>>>
>>>> I would include an explicit "dev.off()" after the plotting; I'm not sure
>>>> all devices guarantee a clean shutdown when R quits.
>>>
>>> And for the record, both littler and Rscript can do that without the
>>> need for double quotes, at least under Linux.  E.g. both
>>>
>>> $ r -e 'postscript(file="", command="cat"); plot(0)' | head
>>> $ Rscript -e 'postscript(file="", command="cat"); plot(0)' | head
>>>
>>> provide the same output (of the beginning of the postscript output).
>>> Our r is as usual somewhat faster, not that this matters in this
>>> non-repeat context.
>>>
>>> Dirk
>>>
>>> --
>>> Three out of two people have difficulties with fractions.
>>>
>>
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>