R help - Jan 2011 - count of factors

Hello everyone,

I have a data set like this:
> head( fish_transect)
  ID_TRANSECT ID_PROJECT   DE_ZONE DE_LOCALITY DE_SECTOR MES
1          42         MB Tarragona    Creixell Control I   9
2          42         MB Tarragona    Creixell Control I   9
3          42         MB Tarragona    Creixell Control I   9
4          42         MB Tarragona    Creixell Control I   9
5          42         MB Tarragona    Creixell Control I   9
6          42         MB Tarragona    Creixell Control I   9
               ID_SPECIES         WEIGHT  SIZE   N    FAMILIA
1 Spondyliosoma cantharus    15.64     10     1    Sparidae
2  Symphodus melanocercus  11.21     10      1   Labridae
3       Diplodus vulgaris         30.20     10      2   Sparidae
4       Diplodus vulgaris         52.24     12      2   Sparidae
5         Diplodus sargus        221.41    14     5    Sparidae
6      Diplodus annularis         3.47       6      1    Sparidae

The table function of the column FAMILIA gives:
Apogonidae     Atherinidae       Blennidae      Blenniidae        Bothidae 
            216               1             406               2             
11 
     Carangidae Centracanthidae       Congridae         Gadidae        
Gobidae 
             25               4              21               2            
214 
     Haemulidae        Labridae       Mugilidae        Mullidae     
Muraenidae 
             25            6381              10             965             
45 
   Myliobatidae      Sciaenidae      Scombridae    Scorpaenidae     
Serranidae 
              2             159               1             512           
2127 
       Sparidae    Sphyraenidae    Synodontidae    Torpedinidae    
Trachinidae 
           6196               5               1               1              
1 
  Tripterygidae 
            135

I want to add a new column "familia2" where those families with low
number
of individuals are listed as "other", that is, for these families
Atherinidae      Blenniidae        Bothidae      Carangidae Centracanthidae 
              1               2              11              25              
4 
      Congridae         Gadidae      Haemulidae       Mugilidae     
Muraenidae 
             21               2              25              10             
45 
   Myliobatidae      Scombridae    Sphyraenidae    Synodontidae   
Torpedinidae 
              2               1               5               1              
1 
    Trachinidae 
              1

I want them in column "familia2" to be named "others"

I've been trying to do a loop telling R to write "others" when the
sum of
FAMILIA was less than 50, but it didn't work because FAMILIA is a factor,
and there isn't a "count" function (or I didn't find it). I
also tried other
options like the "match" function, "level" function, etc. I
know I can do it
manually typing by myself the names of the 16 families but I want to learn a
way to do where I don't need to type the names.

Thanks in advance!

Lucia


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Hi

r-help-bounces at r-project.org napsal dne 19.01.2011 09:51:43:
> 
> Hello everyone,
> 
> I have a data set like this:
> 
> > head( fish_transect)
>   ID_TRANSECT ID_PROJECT   DE_ZONE DE_LOCALITY DE_SECTOR MES
> 1          42         MB Tarragona    Creixell Control I   9
> 2          42         MB Tarragona    Creixell Control I   9
> 3          42         MB Tarragona    Creixell Control I   9
> 4          42         MB Tarragona    Creixell Control I   9
> 5          42         MB Tarragona    Creixell Control I   9
> 6          42         MB Tarragona    Creixell Control I   9
>                ID_SPECIES         WEIGHT  SIZE   N    FAMILIA
> 1 Spondyliosoma cantharus    15.64     10     1    Sparidae
> 2  Symphodus melanocercus  11.21     10      1   Labridae
> 3       Diplodus vulgaris         30.20     10      2   Sparidae
> 4       Diplodus vulgaris         52.24     12      2   Sparidae
> 5         Diplodus sargus        221.41    14     5    Sparidae
> 6      Diplodus annularis         3.47       6      1    Sparidae
> 
> The table function of the column FAMILIA gives:
<snip>
> 
> I want to add a new column "familia2" where those families with
low
number
> of individuals are listed as "other", that is, for these families
> Atherinidae      Blenniidae        Bothidae      Carangidae 
Centracanthidae 
>               1               2              11              25  
> 4 
>       Congridae         Gadidae      Haemulidae       Mugilidae 
> Muraenidae 
>              21               2              25              10  
> 45 
>    Myliobatidae      Scombridae    Sphyraenidae    Synodontidae 
> Torpedinidae 
>               2               1               5               1  
> 1 
>     Trachinidae 
>               1
> 
Use levels
make new column 
fish_transect$familia2 <- fish_transect$familia

change levels
levels(fish_transect$familia2)[which(table(fish_transect$familia2)<46)]<-"other"

You can use any threshold number.

Regards
Petr

BTW you need to have familia as factor not as character variable.


> I want them in column "familia2" to be named "others"
> 
> I've been trying to do a loop telling R to write "others"
when the sum
of
> FAMILIA was less than 50, but it didn't work because FAMILIA is a 
factor,
> and there isn't a "count" function (or I didn't find it).
I also tried
other
> options like the "match" function, "level" function,
etc. I know I can
do it
> manually typing by myself the names of the 16 families but I want to 
learn a
> way to do where I don't need to type the names.
> 
> Thanks in advance!
> 
> Lucia
> 
> 
> -- 
> View this message in context: 
http://r.789695.n4.nabble.com/count-of-factors-
> tp3224791p3224791.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Thanks a lot Petr!! It worked! 

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