Remove levels

Hi,
Not sure if the OP is concerned about this:
Using David's data

?str(DATA)
#'data.frame':??? 15 obs. of? 2 variables:
# $ UnitName_1: Factor w/ 3 levels "lake","pond",..: 3 3 1 3 2 2 3 1 2 3 ...
?#$ Var?????? : int? 95 97 12 47 54 86 14 92 88 8 ...
?toBeRemoved1 <- which(DATA$UnitName_1=="lake")
?DATA <- DATA[-toBeRemoved1,]
?str(DATA)
#'data.frame':??? 12 obs. of? 2 variables:
# $ UnitName_1: Factor w/ 3 levels "lake","pond",..: 3 3 3 2 2 3 2 3 2 3 ...
# $ Var?????? : int? 95 97 47 54 86 14 88 8 99 35 ...
?levels(DATA[,1])
#[1] "lake"? "pond"? "river" ############
?DATA[,1]<- factor(DATA[,1])
?str(DATA)
#'data.frame':??? 12 obs. of? 2 variables:
# $ UnitName_1: Factor w/ 2 levels "pond","river": 2 2 2 1 1 2 1 2 1 2 ...
# $ Var?????? : int? 95 97 47 54 86 14 88 8 99 35 ...
?levels(DATA[,1])
#[1] "pond"? "river"


A.K.



----- Original Message -----
From: David Carlson <dcarlson at tamu.edu>
To: 'Shane Carey' <careyshan at gmail.com>; r-help at r-project.org
Cc: 
Sent: Thursday, June 13, 2013 10:00 AM
Subject: Re: [R] Remove levels

Works fine for me. Too bad you didn't include actual data:

set.seed(42)
DATA <- data.frame(UnitName_1=factor(sample(c("lake", "pond",

"river"),
+? ? ? ?  15, replace=TRUE)), Var=sample.int(100, 15))

DATA

?  UnitName_1 Var
1? ? ?  river? 95
2? ? ?  river? 97
3? ? ? ? lake? 12
4? ? ?  river? 47
5? ? ? ? pond? 54
6? ? ? ? pond? 86
7? ? ?  river? 14
8? ? ? ? lake? 92
9? ? ? ? pond? 88
10? ? ? river?  8
11? ? ?  pond? 99
12? ? ? river? 35
13? ? ? river? 80
14? ? ?  lake? 39
15? ? ?  pond? 72

toBeRemoved1 <- which(DATA$UnitName_1=="lake")
toBeRemoved1

[1]? 3? 8 14

DATA <- DATA[-toBeRemoved1,]
DATA

?  UnitName_1 Var
1? ? ?  river? 95
2? ? ?  river? 97
4? ? ?  river? 47
5? ? ? ? pond? 54
6? ? ? ? pond? 86
7? ? ?  river? 14
9? ? ? ? pond? 88
10? ? ? river?  8
11? ? ?  pond? 99
12? ? ? river? 35
13? ? ? river? 80
15? ? ?  pond? 72

-------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of Shane Carey
Sent: Thursday, June 13, 2013 7:03 AM
To: r-help at r-project.org
Subject: [R] Remove levels

I have a dataframe consisting of factors in one column. Im trying to
remove
certain levels using the following code:
toBeRemoved1<-which(DATA$UnitName_1=="lake")
DATA<-DATA[-toBeRemoved1,]

However it will not remove the level "lake"

In the past this worked for me, but its not working now. Any help
appreciated.

Thanks

Shane

??? [[alternative HTML version deleted]]

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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.