R help - Feb 2013 - help with creating new variables using a loop

Hi there,

I've got a set of 10 numeric variables called Mood1 to Mood10 in a dataset
called mood.  I'm trying to create a set of 10 new variables called m1 to
m10 so that m1=Mood1*1, m2=Mood2*2, etc to m10=Mood10*10

Trawling through the internet, I eventually tried the following code:

for (i in 1:10){
  assign(x=paste0("mood$m",i),
         value=paste0("mood$Mood",i)*i,
         envir=.GlobalEnv)
}

unfortunately this doesn't work as it seems the paste0 function returns a
list object that only contains the vector's name and not the vector itself.

Hope someone can help...

Christel
 		 	   		  
	[[alternative HTML version deleted]]

On Thu, Feb 7, 2013 at 4:16 PM, christel lacaze
<christellacaze at hotmail.co.uk> wrote:
>
> Hi there,
>
> I've got a set of 10 numeric variables called Mood1 to Mood10 in a
dataset called mood.
 That's where you went wrong in the first place. Don't use variable
names for indexing purposes.

 You should have created one variable, a list, where each element is
one of your Mood1, Mood2 etc variables. You can do that:

Mood = list(Mood1,Mood2,Mood3 [etc])

 but its easier to create the right thing in the first place.

 Then looping is simple, and intuitive. Just get Mood2[[i]] where i is
your loop variable. No mucking with paste and get and all that stuff
we should have left behind years ago...
>  I'm trying to create a set of 10 new variables called m1 to m10 so
that m1=Mood1*1, m2=Mood2*2, etc to m10=Mood10*10
 What you mean is you want to create a new variable, a list, with 10 elements.

 m = list()
 for(i in 1:10){m[[i]]=i*Mood[[i]]}

or even:

 m = lapply(1:10,function(i){i*Mood[[i]]})

this kind of thing is so much easier once you've put everything in an
indexable list, I'm not going to tell you how to paste names together.
It can be done, but... yuck.

Barry

On 07.02.2013 17:16, christel lacaze wrote:
>
> Hi there,
>
> I've got a set of 10 numeric variables called Mood1 to Mood10 in a
dataset called mood.  I'm trying to create a set of 10 new variables called
m1 to m10 so that m1=Mood1*1, m2=Mood2*2, etc to m10=Mood10*10
>
> Trawling through the internet, I eventually tried the following code:
>
> for (i in 1:10){
>    assign(x=paste0("mood$m",i),
>           value=paste0("mood$Mood",i)*i,
>           envir=.GlobalEnv)
> }
>

Indexing works via

mood[[paste0("Mood", i)]]


However, assignment to separate objects is typically a bad idea, just 
aollect them in another data.frame or list.

Uwe Ligges






> unfortunately this doesn't work as it seems the paste0 function returns
a list object that only contains the vector's name and not the vector
itself.
>
> Hope someone can help...
>
> Christel
>   		 	   		
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org 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.
>

Hi,
?mood<- data.frame(Mood1=1:5,Mood2=6:10,Mood3=11:15)
lapply(seq_along(mood),function(i) i*mood[i])
A.K.




----- Original Message -----
From: christel lacaze <christellacaze at hotmail.co.uk>
To: r-help at r-project.org
Cc: 
Sent: Thursday, February 7, 2013 11:16 AM
Subject: [R] help with creating new variables using a loop


Hi there,

I've got a set of 10 numeric variables called Mood1 to Mood10 in a dataset
called mood.? I'm trying to create a set of 10 new variables called m1 to
m10 so that m1=Mood1*1, m2=Mood2*2, etc to m10=Mood10*10

Trawling through the internet, I eventually tried the following code:

for (i in 1:10){
? assign(x=paste0("mood$m",i),
? ? ? ?  value=paste0("mood$Mood",i)*i,
? ? ? ?  envir=.GlobalEnv)
}

unfortunately this doesn't work as it seems the paste0 function returns a
list object that only contains the vector's name and not the vector itself.

Hope someone can help...

Christel
??? ???  ??? ?  ??? ??? ? 
??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org 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.

Hi,

Just to add:
If the columns are ?not in the order (Mood1:Mood10) in the dataset.?
mood<- data.frame(Mood2=6:10,Mood1=1:5,Mood10=11:15,Mood3=16:20)?
do.call(cbind,lapply(names(mood),function(i)
mood[i]*as.numeric(gsub("\\D+","",i))))

# ?Mood2 Mood1 Mood10 Mood3
#1 ? ?12 ? ? 1 ? ?110 ? ?48
#2 ? ?14 ? ? 2 ? ?120 ? ?51
#3 ? ?16 ? ? 3 ? ?130 ? ?54
#4 ? ?18 ? ? 4 ? ?140 ? ?57
#5 ? ?20 ? ? 5 ? ?150 ? ?60
A.K.


----- Original Message -----
From: christel lacaze <christellacaze at hotmail.co.uk>
To: r-help at r-project.org
Cc: 
Sent: Thursday, February 7, 2013 11:16 AM
Subject: [R] help with creating new variables using a loop


Hi there,

I've got a set of 10 numeric variables called Mood1 to Mood10 in a dataset
called mood.? I'm trying to create a set of 10 new variables called m1 to
m10 so that m1=Mood1*1, m2=Mood2*2, etc to m10=Mood10*10

Trawling through the internet, I eventually tried the following code:

for (i in 1:10){
? assign(x=paste0("mood$m",i),
? ? ? ?  value=paste0("mood$Mood",i)*i,
? ? ? ?  envir=.GlobalEnv)
}

unfortunately this doesn't work as it seems the paste0 function returns a
list object that only contains the vector's name and not the vector itself.

Hope someone can help...

Christel
??? ???  ??? ?  ??? ??? ? 
??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org 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.