R help - Feb 2010 - remove a row from a dataframe, row names disappear

I find this odd because it doesn't appear to happen in larger datasets. I
have the following data set ENV with the first column set as row.names:
> ENV
         TPlog
001S29H  0.601
002S42H  0.602
003S43S  0.779
004S43S  0.702
005S51H  0.978
006S52P  2.718

If I apply > ENV <- ENV[-1,]  # remove first row of data (right?)
...ENV comes back as:

[1] 0.602 0.779 0.702 0.978 2.718

So I am losing the row name info. I also notice that, if the first two
values in the TPlog column are the same, both values are removed! What's
going on, and why does this same thing not happen in more complex datasets
with more than one column of values?

Many thanks - Euan.

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You're not only removing a row of data, you are invoking the default
behavior of subset, which is to collapse the subsetted result to the
smallest possible type, which in this case is a vector. Vectors have
no rows, and thus no row names.

You need the drop=FALSE argument, as in
ENV <- ENV[-1, , drop=FALSE]

Sarah

On Fri, Feb 5, 2010 at 9:44 AM, Euan Reavie <euan.reavie at gmail.com>
wrote:
> I find this odd because it doesn't appear to happen in larger datasets.
I
> have the following data set ENV with the first column set as row.names:
>
>> ENV
> ? ? ? ? TPlog
> 001S29H ?0.601
> 002S42H ?0.602
> 003S43S ?0.779
> 004S43S ?0.702
> 005S51H ?0.978
> 006S52P ?2.718
>
> If I apply > ENV <- ENV[-1,] ?# remove first row of data (right?)
> ...ENV comes back as:
>
> [1] 0.602 0.779 0.702 0.978 2.718
>
> So I am losing the row name info. I also notice that, if the first two
> values in the TPlog column are the same, both values are removed!
What's
> going on, and why does this same thing not happen in more complex datasets
> with more than one column of values?
>
> Many thanks - Euan.

-- 
Sarah Goslee
http://www.functionaldiversity.org