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