[R] remove 0 rows from a data frame

[Gabor Grothendieck]

Append a dummy row which is always deleted:

nft <- 0
n <- nrow( temp )
temp0 <- rbind( temp, temp[n,] )
temp0[ -c( sample( n, nft ), n+1 ) , ]

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Date: Sun, 23 Nov 2003 18:30:27 +0100 
From: Tord Snall <tord.snall at ebc.uu.se>
To: <r-help at r-project.org> 
Subject: [R] remove 0 rows from a data frame 

 
 
Dear all,

As part of a larger function, I am randomly removing rows from a data
frame. The number of removed rows is determmined by a Poisson distribution
with a low mean. Sometimes, the random number is 0, and that's when the
problem starts:

My data frame:
> temp
occ x y dbh age
801 0 2977.196 3090.225 6 36.0
802 0 2951.892 3083.769 8 40.6
803 0 2919.111 3075.557 8 40.6
804 0 2914.123 3072.700 9 42.9
805 0 2925.353 3074.675 8 40.6

How many rows (nft) shall be removed?
> nft<- rpois(1, 2)
> nft
[1] 2

Ok remove 2 rows:

> temp2<- temp[-sample(nrow(temp), nft), ]
> temp2
occ x y dbh age
801 0 2977.196 3090.225 6 36.0
803 0 2919.111 3075.557 8 40.6
805 0 2925.353 3074.675 8 40.6

No problem.


However, sometimes rpois(1, 2) lead to nft=0, and in that case I do not want 

> temp2<- temp[-sample(nrow(temp), 0), ]
> temp2
[1] occ x y dbh age
<0 rows> (or 0-length row.names)
> 

Instead I want
> temp2<- temp
> temp2
occ x y dbh age
801 0 2977.196 3090.225 6 36.0
802 0 2951.892 3083.769 8 40.6
803 0 2919.111 3075.557 8 40.6
804 0 2914.123 3072.700 9 42.9
805 0 2925.353 3074.675 8 40.6


Could someone help whith that?


Thanks in advance!


Sincerely,
Tord



-----------------------------------------------------------------------
Tord Snäll
Avd. f växtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
Villavägen 14               
SE-752 36 Uppsala, Sweden
Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
E-mail: Tord.Snall at ebc.uu.se
Check this: http://www.vaxtbio.uu.se/resfold/snall.htm!