I see now, thanks for explaining that. Would it be for you to add data.table
methods to ddply then, for this to happen? Or does a ddply method need to
be added to data.table?
"hadley wickham" wrote in message
news:f8e6ff051001200825q4009a122m122082a9df5fe...@mail.gmail.com...
> On Wed, Jan 20
On Wed, Jan 20, 2010 at 8:43 AM, Matthew Dowle wrote:
> Sounds like a good idea. Would it be possible to give an example of how to
> combine plyr with data.table, and why that is better than a data.table only
> solution ?
Well, ideally, you'd do:
adt <- data.table(a)
ans2 <- ddply(a, c("var1", "
Sounds like a good idea. Would it be possible to give an example of how to
combine plyr with data.table, and why that is better than a data.table only
solution ?
"hadley wickham" wrote in message
news:f8e6ff051001200624r2175e38xf558dc8fa3fb6...@mail.gmail.com...
> Note that in the documentaton
> Note that in the documentaton ?"[.data.table" where I say that 'by' is slow,
> I mean relative to how fast it could be. Its seems, in this specific
> example anyway, and with the code posted so far, to be significantly faster
> than sqldf and plyr.
Of course the best of both worlds would be to
The user wrote in their first post :
> I have a lot of observations in my dataset
Heres one way to do it with a data.table :
a=data.table(a)
ans = a[ , list(dt=dt[dt-min(dt)<7]) , by="var1,var2,var3"]
class(ans$dt) = "Date"
Timings are below comparing the 3 methods. In
Using data frame, a, from the post below this is how it would be done
in SQL using sqldf. We join together the original table, a, with a
table of minimums (computed by the nested select) and then choose only
the rows where dt - mindt < 7 (in the where clause).
> library(sqldf)
> sqldf("select va
On Mon, Jan 18, 2010 at 1:54 PM, Bert Gunter wrote:
> One way to do it:
>
> 1. Convert your date column to the Date class using the as.Date() function.
> This allows you to do the necessary arithmetic on the dates below.
> dt <- as.Date(a[,4],"%d/%m/%Y")
>
> 2. Create a factor out of your first th
p
Cc: Bert Gunter; r-help@r-project.org
Subject: Re: [R] problem of data manipulation
I just remembered that my actual dataset for var2 and var3
are numerical data,e.g. 12.34, not factors. The above example data is
misleading.
Suppose var2 and var3 are numerical variables, not factors. How shoul
> > -Original Message-
> > From: Bert Gunter [mailto:gunter.ber...@gene.com]
> > Sent: Monday, January 18, 2010 12:32 PM
> > To: William Dunlap; 'rusers.sh'; r-help@r-project.org
> > Subject: RE: [R] problem of data manipulation
> >
> > Absolutely... so
Thank you so much. I got it.
2010/1/18 William Dunlap
> > -Original Message-
> > From: Bert Gunter [mailto:gunter.ber...@gene.com]
> > Sent: Monday, January 18, 2010 12:32 PM
> > To: William Dunlap; 'rusers.sh'; r-help@r-project.org
> > Subje
> -Original Message-
> From: Bert Gunter [mailto:gunter.ber...@gene.com]
> Sent: Monday, January 18, 2010 12:32 PM
> To: William Dunlap; 'rusers.sh'; r-help@r-project.org
> Subject: RE: [R] problem of data manipulation
>
> Absolutely... so long as yo
:15 PM
To: Bert Gunter; rusers.sh; r-help@r-project.org
Subject: Re: [R] problem of data manipulation
> -Original Message-
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of Bert Gunter
> Sent: Monday, January 18, 2010 11:54 AM
> To:
> -Original Message-
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of Bert Gunter
> Sent: Monday, January 18, 2010 11:54 AM
> To: 'rusers.sh'; r-help@r-project.org
> Subject: Re: [R] problem of data manipulation
&
ject.org] On
Behalf Of rusers.sh
Sent: Monday, January 18, 2010 10:40 AM
To: r-help@r-project.org
Subject: [R] problem of data manipulation
Hello,
See my problem below.
a<-data.frame(c("s","c","c","n","n","n"),c(rep(1,3),rep(2,3)),c(rep(
Hello,
See my problem below.
a<-data.frame(c("s","c","c","n","n","n"),c(rep(1,3),rep(2,3)),c(rep(2,3),rep(1,3)),c("01/01/1999","10/02/2000","13/02/2000","11/02/2000","15/02/2000","23/02/2000"))
colnames(a)<-c("var1","var2","var3","var4")
> a
var1 var2 var3 var4
1s1201/01/1
15 matches
Mail list logo
