Remove Rows Based on Factor

Hi,
May be this helps:
ZZ<- data.frame(Index=c("2006-04-07","2006-04-08","2007-01-01","2007-01-01","2008-01-04","2008-01-04"),Open=c(17.5,17.6,16.8,17.2,17.3,17.5),High=c(18.2,17.6,17.2,17.2,17.5,17.6),Low=c(17.3,16.8,16.8,16.8,16.2,15.8),Close=c(17.5,16.8,17.1,16.8,15.9,16.2),Volume=c(23834500,2916000,1453700,991400,443522,38990),Adjusted=c(16.8,16.2,16.4,16.2,16.5,17.6))
ZZ$Index<- as.Date(ZZ$Index,format="%Y-%m-%d")
library(xts)
?ZZ1<-xts(ZZ[,-1],ZZ[,1])
ZZ1
#?????????? Open High? Low Close?? Volume Adjusted
#2006-04-07 17.5 18.2 17.3? 17.5 23834500???? 16.8
#2006-04-08 17.6 17.6 16.8? 16.8? 2916000???? 16.2
#2007-01-01 16.8 17.2 16.8? 17.1? 1453700???? 16.4
#2007-01-01 17.2 17.2 16.8? 16.8?? 991400???? 16.2
#2008-01-04 17.3 17.5 16.2? 15.9?? 443522???? 16.5
#2008-01-04 17.5 17.6 15.8? 16.2??? 38990???? 17.6

Suppose, I wanted to get only the rows starting from "2006-04-08"
?ZZ1['2006-04-08/']
#?????????? Open High? Low Close? Volume Adjusted
#2006-04-08 17.6 17.6 16.8? 16.8 2916000???? 16.2
#2007-01-01 16.8 17.2 16.8? 17.1 1453700???? 16.4
#2007-01-01 17.2 17.2 16.8? 16.8? 991400???? 16.2
#2008-01-04 17.3 17.5 16.2? 15.9? 443522???? 16.5
#2008-01-04 17.5 17.6 15.8? 16.2?? 38990???? 17.6
A.K.




----- Original Message -----
From: "Sparks, John James" <jspark4 at uic.edu>
To: r-help at r-project.org
Cc: 
Sent: Monday, April 15, 2013 12:58 PM
Subject: [R] Remove Rows Based on Factor

Dear R Helpers,

I did a search for deleting rows based on conditions but wasn't able to
find an example that addressed the error that I am getting.? I am hoping
that this is a simple syntax phenomenon that somebody else knows off the
top of their head.? My apologies for not providing a reproducible example
but I think that the information given will allow someone to give me a
hint.

I want to delete the rows of the data frame ZZ where Index is earlier that
Jan 1 of 2007.? That Index column is a factor.? When I tired a couple of
different methods, I got the error shown below.? Can anybody tell me what
I am doing wrong?? I would really appreciate it.

--John Sparks

str(ZZ)

'data.frame':?  1584 obs. of? 7 variables:
$ Index?  : Factor w/ 1583 levels "2006-04-07","2006-04-10",..: 1 2 3 4 5
6 7 8 9 10 ...
$ Open? ? : num? 17.5 17.6 16.8 17.2 17 ...
$ High? ? : num? 18.2 17.6 17.2 17.2 17.1 ...
$ Low? ?  : num? 17.3 16.8 16.8 16.8 16.6 ...
$ Close?  : num? 17.5 16.8 17.1 16.8 16.7 ...
$ Volume? : num? 23834500 2916000 1453700 991400 967400 ...
$ Adjusted: num? 16.8 16.2 16.4 16.2 16 ...

test<-ZZ[ZZ$Index>"2007-01-01",]

Warning message:
In Ops.factor(ZZ$Index, "2007-01-01") : > not meaningful for factors

test<-subset(ZZ,Index>2007-01-01)

Warning message:
In Ops.factor(Index, 2007 - 1 - 1) : > not meaningful for factors

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