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Horace Tso

2006-Aug-11 18:48 UTC

[R] An apply and rep question

Hi list,

I'm sure the explanation must be laughably simple to the experts out
there, but I just could figure it out. I have a simple data frame that
looks like,
>head(da.off)       DDate  OffP
1 2005-01-01 41.23
2 2005-01-02 44.86
3 2005-01-03 44.86
4 2005-01-04 43.01
5 2005-01-05 45.47
6 2005-01-06 48.62

where the first column DDate currently is character, and OffP is
numeric. 

I want to duplicate every row 2 times, so I thought I use apply(),

x <- apply(da.off, 2, rep, each=2) 

The result is a matrix of all character,

 head(x)
  DDate        OffP    
1 "2005-01-01" " 41.23"
1 "2005-01-01" " 41.23"
2 "2005-01-02" " 44.86"
2 "2005-01-02" " 44.86"
3 "2005-01-03" " 44.86"
3 "2005-01-03" " 44.86"

To convert it back to numeric, I did

x <- as.data.frame(x)
x$OffP <- as.numeric(x$OffP)

However, the OffP column didn't convert correctly, a mystery since they
"look" quite alright above. (I know, I know, there seems to be a space
there. But why?)

head(x)
         DDate OffP
1   2005-01-01  150
1.1 2005-01-01  150
2   2005-01-02  202
2.1 2005-01-02  202
3   2005-01-03  202
3.1 2005-01-03  202

Is this the wrong way to use apply or rep? 

Horace

Gabor Grothendieck

2006-Aug-11 19:01 UTC

head link

[R] An apply and rep question

The approach here is to perform the repetition on the indices (or rownames)
rather than on the data frame directly.  Using the builtin data frame BOD
any of the following would work:

BOD[gl(nrow(BOD), 2),]
BOD[rep(1:nrow(BOD), each = 2),]
BOD[rep(rownames(BOD), each = 2),]

On 8/11/06, Horace Tso <Horace.Tso at pgn.com>
wrote:> Hi list,
>
> I'm sure the explanation must be laughably simple to the experts out
> there, but I just could figure it out. I have a simple data frame that
> looks like,
>
> >head(da.off)
>       DDate  OffP
> 1 2005-01-01 41.23
> 2 2005-01-02 44.86
> 3 2005-01-03 44.86
> 4 2005-01-04 43.01
> 5 2005-01-05 45.47
> 6 2005-01-06 48.62
>
> where the first column DDate currently is character, and OffP is
> numeric.
>
> I want to duplicate every row 2 times, so I thought I use apply(),
>
> x <- apply(da.off, 2, rep, each=2)
>
> The result is a matrix of all character,
>
>  head(x)
>  DDate        OffP
> 1 "2005-01-01" " 41.23"
> 1 "2005-01-01" " 41.23"
> 2 "2005-01-02" " 44.86"
> 2 "2005-01-02" " 44.86"
> 3 "2005-01-03" " 44.86"
> 3 "2005-01-03" " 44.86"
>
> To convert it back to numeric, I did
>
> x <- as.data.frame(x)
> x$OffP <- as.numeric(x$OffP)
>
> However, the OffP column didn't convert correctly, a mystery since they
> "look" quite alright above. (I know, I know, there seems to be a
space
> there. But why?)
>
> head(x)
>         DDate OffP
> 1   2005-01-01  150
> 1.1 2005-01-01  150
> 2   2005-01-02  202
> 2.1 2005-01-02  202
> 3   2005-01-03  202
> 3.1 2005-01-03  202
>
> Is this the wrong way to use apply or rep?
>
> Horace
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Liaw, Andy

2006-Aug-11 19:05 UTC

head link

[R] An apply and rep question

The trick is to rep() the index, not the data:

R> dat2 <- dat[rep(1:nrow(dat), each=2), ]
R> dat2
         DDate  OffP
1   2005-01-01 41.23
1.1 2005-01-01 41.23
2   2005-01-02 44.86
2.1 2005-01-02 44.86
3   2005-01-03 44.86
3.1 2005-01-03 44.86
4   2005-01-04 43.01
4.1 2005-01-04 43.01
5   2005-01-05 45.47
5.1 2005-01-05 45.47
6   2005-01-06 48.62
6.1 2005-01-06 48.62

Andy

From: Horace Tso> 
> Hi list,
> 
> I'm sure the explanation must be laughably simple to the 
> experts out there, but I just could figure it out. I have a 
> simple data frame that looks like,
> 
> >head(da.off)
>        DDate  OffP
> 1 2005-01-01 41.23
> 2 2005-01-02 44.86
> 3 2005-01-03 44.86
> 4 2005-01-04 43.01
> 5 2005-01-05 45.47
> 6 2005-01-06 48.62
> 
> where the first column DDate currently is character, and OffP 
> is numeric. 
> 
> I want to duplicate every row 2 times, so I thought I use apply(),
> 
> x <- apply(da.off, 2, rep, each=2) 
> 
> The result is a matrix of all character,
> 
>  head(x)
>   DDate        OffP    
> 1 "2005-01-01" " 41.23"
> 1 "2005-01-01" " 41.23"
> 2 "2005-01-02" " 44.86"
> 2 "2005-01-02" " 44.86"
> 3 "2005-01-03" " 44.86"
> 3 "2005-01-03" " 44.86"
> 
> To convert it back to numeric, I did
> 
> x <- as.data.frame(x)
> x$OffP <- as.numeric(x$OffP)
> 
> However, the OffP column didn't convert correctly, a mystery 
> since they "look" quite alright above. (I know, I know, there 
> seems to be a space there. But why?)
> 
> head(x)
>          DDate OffP
> 1   2005-01-01  150
> 1.1 2005-01-01  150
> 2   2005-01-02  202
> 2.1 2005-01-02  202
> 3   2005-01-03  202
> 3.1 2005-01-03  202
> 
> Is this the wrong way to use apply or rep? 
> 
> Horace
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
>

Horace Tso

2006-Aug-11 19:20 UTC

head link

[R] An apply and rep question

Thanks Gabor, Andy, and Phil. I learn new trick, particularly the use of
gl().

H.
>>> "Gabor Grothendieck" <ggrothendieck at gmail.com>
8/11/2006 12:01 PM
>>>The approach here is to perform the repetition on the indices (or
rownames)
rather than on the data frame directly.  Using the builtin data frame
BOD
any of the following would work:

BOD[gl(nrow(BOD), 2),]
BOD[rep(1:nrow(BOD), each = 2),]
BOD[rep(rownames(BOD), each = 2),]

On 8/11/06, Horace Tso <Horace.Tso at pgn.com>
wrote:> Hi list,
>
> I'm sure the explanation must be laughably simple to the experts out
> there, but I just could figure it out. I have a simple data frame
that> looks like,
>
> >head(da.off)
>       DDate  OffP
> 1 2005-01-01 41.23
> 2 2005-01-02 44.86
> 3 2005-01-03 44.86
> 4 2005-01-04 43.01
> 5 2005-01-05 45.47
> 6 2005-01-06 48.62
>
> where the first column DDate currently is character, and OffP is
> numeric.
>
> I want to duplicate every row 2 times, so I thought I use apply(),
>
> x <- apply(da.off, 2, rep, each=2)
>
> The result is a matrix of all character,
>
>  head(x)
>  DDate        OffP
> 1 "2005-01-01" " 41.23"
> 1 "2005-01-01" " 41.23"
> 2 "2005-01-02" " 44.86"
> 2 "2005-01-02" " 44.86"
> 3 "2005-01-03" " 44.86"
> 3 "2005-01-03" " 44.86"
>
> To convert it back to numeric, I did
>
> x <- as.data.frame(x)
> x$OffP <- as.numeric(x$OffP)
>
> However, the OffP column didn't convert correctly, a mystery since
they> "look" quite alright above. (I know, I know, there seems to be a
space> there. But why?)
>
> head(x)
>         DDate OffP
> 1   2005-01-01  150
> 1.1 2005-01-01  150
> 2   2005-01-02  202
> 2.1 2005-01-02  202
> 3   2005-01-03  202
> 3.1 2005-01-03  202
>
> Is this the wrong way to use apply or rep?
>
> Horace
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help 
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.
>
______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help 
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html 
and provide commented, minimal, self-contained, reproducible code.

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