Message-ID: <Pine.LNX.4.61.0505191909480.13182@gannet.stats>
Date: 2005-05-19T18:12:27Z
From: Brian Ripley
Subject: does column exist?
In-Reply-To: <OFFB688EFD.2F771D67-ON86257006.00621F35-86257006.00624612@mmm.com>
On Thu, 19 May 2005 apjaworski at mmm.com wrote:
> There may be a simpler way, but this
>
> is.na(match("X", names(df)))
>
> should return TRUE if the column name exists and FALSE otherwise.
Mere syntactic sugar, but "X" %in% names(mydf) is self-documenting.
> How do I test if a data.frame has a column named X?
> exists(o) checks if the object exists or not, I want to test if a
> data.frame object (df) has a column names(X), something like:
> exists(df$X)
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595