[R] x[x$a=="q",,drop=TRUE]

From: Mikkel Grum <mi2kelgrum_at_yahoo.com>
Date: Thu 02 Jun 2005 - 04:08:46 EST


I'm trying to select a subset of a dataframe while dropping some factors. While the dataset gets smaller all Factor levels remain and I need to get rid of them. Strangely enough, I am almost certain that the same code on the same data worked OK earlier today - and it is not the first time that I'm not able to replicate earlier results with this command (I know, I might just be going crazy). What am I doing wrong?

I'm working on Windows Server 2003, R 2.1.0 (2005-04-18).

> str(spray)
`data.frame': 370 obs. of 7 variables:
$ PD : Factor w/ 8 levels

"Botrytis","Downy",..: 2 2 2 2 4 2 2 5 5 5 ...
$ postSpmtsQ: num 1309 1309 384 384 1044 ...
$ ante62Q : num 284 284 218 218 366 ...
$ ante08Q : num 331 331 228 228 492 ...

$ ante29Q : num 297 297 1067 1067 1034 ...
$ ante16Q : num 0 0 0.2 0.2 0 0 0 6.7 0 31.5 ...
$ Trt : Factor w/ 41 levels "Acrobat MZ WP",..:
27 5 27 5 36 27 5 24 24 24 ...
> sprayS <- spray[spray$PD == "Spidermites", , drop = TRUE]
> str(sprayS)
`data.frame': 111 obs. of 7 variables:
$ PD : Factor w/ 8 levels

"Botrytis","Downy",..: 5 5 5 5 5 5 5 5 5 5 ...
$ postSpmtsQ: num 13395 31588 84254 136 619 ...
$ ante62Q : num 1357 21187 21819 218 237 ...
$ ante08Q : num 973 21740 25112 228 134 ...
$ ante29Q : num 2103 106970 66676 1067 119
...
$ ante16Q : num 6.7 0 31.5 0.2 0 0 0 0 14.3 0 ...
$ Trt : Factor w/ 41 levels "Acrobat MZ WP",..:
24 24 24 24 24 24 24 24 24 24 ...
> table(sprayS$Trt)

    Acrobat MZ WP           Agrifos      Apollo 50 SC 
          CALMAG 
                0                 0                13 
               0 
            DM-31    Dynamec 1.8 EC   Equation Pro DF 
       Evisect S 
                0                13                 0 
               0 
            Flint         Floramite           Impulse 
          Karate 
                0                15                 0 
               0 
      Karate zeon            Melody    Meltatox 40 EC 
             MKP 
                0                 0                 0 
               0 
         Molasses       Nembicidine     Nimrod 250 EC 
  Nissorun 10 EC 
                0                 0                 0 
              12 
           Oberon     Orthene 75 WP       Oscar 20 SC 
         Pegasus 
               15                 0                 9 
              26 
     Polar 50 WSG            Potfos          Proplant 
           Pyrus 
                0                 0                 0 
               0 
Ridomil MZ 63 5WP   Rovral aqua flo      Score 250 EC 
    Secure 36 SC 
                0                 0                 0 
               8 
      Sequestrone          Shavit f         Sporekill 
    Stroby 50 WG 
                0                 0                 0 
               0 
           Switch            Tracer          Trafos K 
        Vandozeb 
                0                 0                 0 
               0 
          Vitomex 
                0 

cheers,
Mikkel



R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jun 02 04:12:59 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:32:20 EST