[Rcpp-devel] retrieve the column names of Rcpp::DataFrame

[Chaomei Lo]

Thanks a lot for help. Kevin.

You are correct, both df.attr("names") and df.names() work.

Chaomei




On Thu, Jul 10, 2014 at 5:14 PM, Kevin Ushey <kevinushey at gmail.com> wrote:

> df.attr("names") ? data.frames do not have a column names attribute.
> Neither do matrices, for that matter, which have an (optional) `dimnames`
> attribute.
>
> Please see: http://gallery.rcpp.org/articles/setting-object-attributes/,
> and also try looking at what e.g. `attributes(data.frame(x=1))`, for
> example, gives you to have a hint at what attributes you can poke at and
> how.
>
> Cheers,
> Kevin
>
>
> On Thu, Jul 10, 2014 at 5:09 PM, Chaomei Lo <chaomeilo at gmail.com> wrote:
>
>> I have a R data frame pass to the Rcpp function, for example in below-
>>
>> void myDataFrame(Rcpp::DataFrame df) {
>> ....
>> }
>>
>> I would need to know the column names first before I retrieve the
>> data but df.colnames() does not work but the df.length() and df.nrows()
>> work.
>>
>> Thanks for help !
>> Chaomei
>>
>>
>>
>>
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>> Rcpp-devel at lists.r-forge.r-project.org
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>>
>
>
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