[R] remove 0 rows from a data frame

[Spencer Graves]

Have you considered the complement, e.g.: 

N <- 4
DF <- data.frame(a=1:N, b=1:N)
DF[-1,]
#nft <- rpois(1,2)
nft <- 0
DF[sample(N, N-nft),]

hope this helps.  spencer graves

Tord Snall wrote:

>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!
>
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>  
>