[R] Subset by string name?

[jim holtman]

You need

Yut_are <- subset (Yut, Mark=="Arecaceae", select=c(X, Y, Mark))

for equality test (two "==")

On Sat, Nov 29, 2008 at 5:22 AM, Ophelia Wang
<opheliawang at mail.utexas.edu> wrote:
> 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
>
> --
> Yung-Ho (Ophelia) Wang
> Doctoral Candidate
> Department of Geography and the Environment
> University of Texas
> +1-512-232-1597
> opheliawang at mail.utexas.edu
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?