[R] Bug

[dhansekaran]

Thank you very much for help. Here is my values of Sale Date 

>sample

    test[1:100, 76]
1        1989-08-01
2        1900-01-01
3        2003-11-18
4        2003-05-30
5        2005-08-18
6        1990-04-01
7        1989-01-01
8        1900-01-01
9        1996-03-12
10       1900-01-01
11       2005-11-14
12       2002-05-08
13       2000-10-10
14       1900-01-01
15       2007-03-27








Gabor Grothendieck wrote:
> 
> You have found a bug.
> 
> It would be best to use dput(test1) to show unambiguously display what
> is in test1 but in the absence of that I will assume that its as in
> test1 shown below.
> 
>> library(sqldf)
>> test1 <- data.frame(sale_date = as.Date(c("2008-08-01", "2031-01-09",
> + "1990-01-03", "2007-02-03", "1997-01-03", "2004-02-04")))
> 
>> sqldf("select max(sale_date) from test1")
>   max(sale_date)
> 1         9864.0
> 
> Evidently it is taking the internal numeric representation and then
> storing it in the database as characters and then taking the maximum
> of those characters.  As the fifth entry starts with 9 its the maximum
> when sorted alphabetically:
> 
>> as.numeric(test1[[1]])
> [1] 14092 22288  7307 13547  9864 12452
> 
> I will have to investigate whether the problem is in sqldf or the
> underlying software.  In the meantime if you represent the Date data
> as character you should be ok:
> 
>> test2 <- transform(test1, sale_date = as.character(sale_date))
>> sqldf("select max(sale_date) from test2")
>   max(sale_date)
> 1     2031-01-09
> 
> 
> 
> 
>> packageDescription("sqldf")$Version
> [1] "0-1.7"
>> R.version.string
> [1] "R version 2.9.2 Patched (2009-09-08 r49647)"
> 
> Please provide the output of dput(test1) so that we know unambiguously
> what your data looks like.
> 
> On Thu, Sep 24, 2009 at 9:07 AM, dhanasekaran <dhana.sa at gmail.com> wrote:
>> The data looks like
>>
>> "2008-08-01"
>> "2031-01-09"
>> "1990-01-03"
>> "2007-02-03"
>> "1997-01-03"
>> "2004-02-04"
>>
>> Thanks.
>>
>> On Thu, Sep 24, 2009 at 5:20 PM, Gabor Grothendieck
>> <ggrothendieck at gmail.com> wrote:
>>>
>>> Please read and follow the last line to every message on r-help.
>>>
>>> On Thu, Sep 24, 2009 at 5:32 AM, dhansekaran <dhana.sa at gmail.com> wrote:
>>> >
>>> > Hello R users
>>> >
>>> > I tried to get maximum of sale date from my dataframe using sqldf in
>>> R.
>>> > First time when i was executing the following code
>>> >
>>> >>sqldf("select max(sale_date) from test1")
>>> >
>>> > i got the result as 9997.0
>>> >
>>> > BUT
>>> >
>>> > when i was running the same for second time, the result was 2031-04-09
>>> > (this
>>> > is what correct one!)
>>> >
>>> > why it was happened?
>>> >
>>> > thanks.
>>> > --
>>> > View this message in context:
>>> > http://www.nabble.com/Bug-tp25548042p25548042.html
>>> > Sent from the R help mailing list archive at Nabble.com.
>>> >
>>> > ______________________________________________
>>> > R-help at r-project.org mailing list
>>> > https://stat.ethz.ch/mailman/listinfo/r-help
>>> > PLEASE do read the posting guide
>>> > http://www.R-project.org/posting-guide.html
>>> > and provide commented, minimal, self-contained, reproducible code.
>>> >
>>
>>
>>
>> --
>> Best
>> Dhanasekaran
>>
>> "Without trust, words become the hollow sound of a wooden gong. With
>> trust,
>> words become life itself.”
>>
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> 

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