[R] Filtering on a dataframe- newbie question

[Peter Ehlers]

Rolf Turner wrote:
> 
> On 19/10/2009, at 4:23 PM, milton ruser wrote:
> 
>> Hi there,
>>
>> Try ?subset
> 
>     No. Don't.
> 
>     Just do:
> 
>     X <- dataframe[dataframe$Name=='T44',]
> 
>     Note the comma in the penultimate position.
> 
>     Read up on array indexing; see ?"[" and An Introduction to R,
>     section 5.2 for starters.
> 
>     A data frame is two dimensional; you were basically trying to
>     treat it as one dimensional.
> 
>     And don't call your data frame ``dataframe''.  Would you
>     call your dog ``dog''?  (Pace Barry Rowlingson! :-) )
> 
>         cheers,
> 
>             Rolf Turner
> 
>> ?str may also be useful..
> 
>     str is indeed useful --- but not here.

Rolf, I would disagree. For anyone new to R, it's a good idea
to use str() after any operation they were sufficiently
unsure about to ask for help.

Cheers,

  -Peter Ehlers

> 
>             R. T.
>>
>> bests
>>
>> milton
>>
>> On Sun, Oct 18, 2009 at 11:10 PM, ANJAN PURKAYASTHA <
>> anjan.purkayastha at gmail.com> wrote:
>>
>>> Hi,
>>> newbie question. I have a data-frame with 3 named columns: Name, Obs1,
>>> Obs2.
>>> The Name column members are made of alphanumeric characters: T1, T2, T3
>>> etc.
>>> I would like to acess only that subset of the data-frame with Name == 
>>> T44.
>>> X <- dataframe[dataframe$Name=='T44'] does not work.
>>> Any ideas on how to do this?
>>> I'm sure I'm missing a simple concept here.
>>>
>>> Thanks,
>>> Anjan
>>>
>>>
>>> -- 
>>> =============================
>>> anjan purkayastha, phd
>>> bioinformatics analyst
>>> whitehead institute for biomedical research
>>> nine cambridge center
>>> cambridge, ma 02142
>>>
>>> purkayas [at] wi [dot] mit [dot] edu
>>> 703.740.6939
>>>
>>>        [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> 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<http://www.r-project.org/posting-guide.html> 
>>>
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>     [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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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> ______________________________________________
> 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.
> 
>