[R] Subset by family name?

[Ophelia Wang]

Sorry to bother everyone---I realized I should have used "==" instead  
of "=" in the subset syntax!


Quoting Ophelia Wang <opheliawang at mail.utexas.edu>:

> Hi all,
>
> I thought this should be very simple, but I'm not sure where the
> problem is. I have a .txt data file that contains X and Y coordinates
> of trees and their family names:
>
> "X"	"Y"	"Mark"
> 0	28	"Sapotaceae"
> 1	30	"Meliaceae"
> 1	40	"Meliaceae"
> 1	60	"Mimosaceae"
> 1	76	"Olacaceae"
> 1.5	73	"Myristicaceae"
> 2	34	"Euphorbiaceae"
> 2	62	"Olacaceae"
> 2	86	"Mimosaceae"
> 2.5	36	"Arecaceae"
> 3	22	"Nyctaginaceae"
> 3	25	"Moraceae"
> 3	38	"Rubiaceae"
> 3	47	"Desconocido "
> 3	99	"Mimosaceae"
> 3.5	24	"Anacardiaceae"
> 3.5	57	"Sapotaceae"
> 4	1	"Lecythidaceae"
>
> Now I just want to work on one family for various spatial analyses in
> ads and spatstats, so I wrote:
>
> Yut <-read.delim(
> "C:/dissertation/data2006/Parcela_1-3/Yutsun_tree.txt", header = TRUE,
> sep = "\t", quote="\"", dec=".", fill = TRUE )
>
> Yut_are <- subset (Yut, Mark="Arecaceae", select=c(X, Y, Mark))
>
> However, the summary of Yut_are still contains trees of other families:
>
>   X                Y                    Mark
>  Min.   :  0.00   Min.   : 0.00   Myristicaceae: 65
>  1st Qu.: 24.00   1st Qu.:24.00   Lecythidaceae: 60
>  Median : 46.00   Median :51.00   Sapotaceae   : 51
>  Mean   : 48.07   Mean   :49.72   Moraceae     : 45
>  3rd Qu.: 72.50   3rd Qu.:75.50   Arecaceae    : 41
>  Max.   :100.00   Max.   :99.00   Mimosaceae   : 34
>                                   (Other)      :313
>
> Please tell me how do I subset a dataset like this to extract trees
> from only one or a few families? Thanks a lot!
>
> Ophelia
>