R help - Dec 2004 - subsetting a data.frame to the 'unique' of a column

Rudi Alberts <r.alberts at rug.nl> writes:

> something like this, however, this gives me the complete df.
> 
> df[df$colname %in% unique(df$colname),]
> 
> or this, which doesnt work
> 
> df[df$colname == unique(df$colname),]

 df[!duplicated(df$colname),]


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907

On Thu, Dec 23, 2004 at 11:28:31AM -0800, Rudi Alberts
wrote:
> Hi,
> 
> I often run into this problem:
> I have a data.frame with one column containing entries that are not
> unique. What I then want is a subset of the data.frame in which
> the entries in that column have become the 'unique' of the original
> column. 
> Normally I program around it by taking the unique of the column and
> making a new data.frame with it and filling the rest of the data.
> 
> (By the way, when moving to the smaller data.frame for example 5 rows
> with the same value in that column will be replaced by one row for that
> value. I don't mind which of the rows now..)
> 
> 
> something like this, however, this gives me the complete df.
> 
> df[df$colname %in% unique(df$colname),]
> 
> or this, which doesnt work
> 
> df[df$colname == unique(df$colname),]
> 
 Use 'duplicated':
> df[!duplicated(df$colname), ]
-- 
 G??ran Brostr??m                    tel: +46 90 786 5223
 Department of Statistics          fax: +46 90 786 6614
 Ume?? University                   http://www.stat.umu.se/egna/gb/
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Hi,

I often run into this problem:
I have a data.frame with one column containing entries that are not
unique. What I then want is a subset of the data.frame in which
the entries in that column have become the 'unique' of the original
column. 
Normally I program around it by taking the unique of the column and
making a new data.frame with it and filling the rest of the data.

(By the way, when moving to the smaller data.frame for example 5 rows
with the same value in that column will be replaced by one row for that
value. I don't mind which of the rows now..)


something like this, however, this gives me the complete df.

df[df$colname %in% unique(df$colname),]

or this, which doesnt work

df[df$colname == unique(df$colname),]


regards, R. Alberts