R help - Jan 2012 - dataframe: how to select an element from a row

Hi, 
I 'd like to select the Date where myvalue =1800 appears the* first time*.

For instance:
df =data.frame(date, myvalue, ...)

...

Date                            myvalue
2012-01-05                2500                
2012-01-06               2450
*2012-01-07               1800*
2012-01-08                2200
2012-01-09                1800

I'd like to retrieve the third line.

I do not find a clean way.

Thanks for your help



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Hi ikuzar,

Try

subset(df, myvalue == 1800, select = Date)[1, ]

See ?subset for more information.

HTH,
Jorge.-


On Thu, Jan 19, 2012 at 6:42 PM, ikuzar <> wrote:
> Hi,
> I 'd like to select the Date where myvalue =1800 appears the* first
time*.
>
> For instance:
> df =data.frame(date, myvalue, ...)
>
> ...
>
> Date                            myvalue
> 2012-01-05                2500
> 2012-01-06               2450
> *2012-01-07               1800*
> 2012-01-08                2200
> 2012-01-09                1800
>
> I'd like to retrieve the third line.
>
> I do not find a clean way.
>
> Thanks for your help
>
>
>
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/dataframe-how-to-select-an-element-from-a-row-tp4311881p4311881.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>
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