R help - Apr 2006 - Creat new column based on condition

Hi,
   
  How can I accomplish this task in R?
   
    V1
    10
    20
    30
    10
    10
    20
     
  Create a new column V2 such that: 
  If V1 = 10 then V2 = 4
  If V1 = 20 then V2 = 6
  V1 =   30 then V2 = 10
   
  So the O/P looks like this
   
    V1  V2
    10   4
    20   6
    30  10
    10   4
    10   4  
    20   6
   
  Thanks in advance.
   
  Sachin

__________________________________________________



	[[alternative HTML version deleted]]

Try:

V1 <- matrix(c(10, 20, 30, 10, 10, 20), nc = 1)

V2 <- 4 * (V1 == 10) + 6 * (V1 == 20) + 10 * (V1 == 30)

or

V2 <- matrix(c(4, 6, 10)[V1/10], nc = 1)

On 4/21/06, Sachin J <sachinj.2006 at yahoo.com>
wrote:
> Hi,
>
>  How can I accomplish this task in R?
>
>    V1
>    10
>    20
>    30
>    10
>    10
>    20
>
>  Create a new column V2 such that:
>  If V1 = 10 then V2 = 4
>  If V1 = 20 then V2 = 6
>  V1 =   30 then V2 = 10
>
>  So the O/P looks like this
>
>    V1  V2
>    10   4
>    20   6
>    30  10
>    10   4
>    10   4
>    20   6
>
>  Thanks in advance.
>
>  Sachin
>
> __________________________________________________
>
>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> 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
>

On 4/21/2006 4:05 PM, Sachin J wrote:
> Hi,
>    
>   How can I accomplish this task in R?
>    
>     V1
>     10
>     20
>     30
>     10
>     10
>     20
>      
>   Create a new column V2 such that: 
>   If V1 = 10 then V2 = 4
>   If V1 = 20 then V2 = 6
>   V1 =   30 then V2 = 10
Gabor's solution is fine; something that looks a little bit more like 
your code is this:

  V2 <- NA
  V2 <- ifelse( V1 == 10, 4, V2)
  V2 <- ifelse( V1 == 20, 6, V2)
  V2 <- ifelse( V1 == 30, 10, V2)

or

  V2 <- ifelse( V1 == 10, 4,
          ifelse( V1 == 20, 6,
            ifelse( V1 == 30, 10, NA )))

(where the NA is to handle any unexpected case where V1 isn't 10, 20 or 
30).  My preference would be to use just one assignment, and if I was 
sure 10, 20 and 30 were the only possibilities, would use

  V2 <- ifelse( V1 == 10, 4,
          ifelse( V1 == 20, 6, 10 ))

Duncan Murdoch
>    
>   So the O/P looks like this
>    
>     V1  V2
>     10   4
>     20   6
>     30  10
>     10   4
>     10   4  
>     20   6
>    
>   Thanks in advance.
>    
>   Sachin
> 
> __________________________________________________
> 
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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

Here is a compact solution using approx:

  DF$V2 <- approx(c(10, 20, 30), c(4,6,10), DF$V1)$y


On 4/21/06, Gabor Grothendieck <ggrothendieck at gmail.com>
wrote:
> DF <- data.frame(V1 = c(10, 20, 30, 10, 10, 20))
> DF$V2 <- with(DF, 4 * (V1 == 10) + 6 * (V1 == 20) + 10 * (V1 == 30))
> DF$V3 <- c(4, 6, 10)[DF$V1/10]
>
> or
>
> DF <- data.frame(V1 = c(10, 20, 30, 10, 10, 20))
> DF <- transform(DF, V2 = 4 * (V1 == 10) + 6 * (V1 == 20) + 10 * (V1 ==
30),
>  V3 = c(4, 6, 10)[V1/10])
>
> On 4/21/06, Sachin J <sachinj.2006 at yahoo.com> wrote:
> >
> > Hi Gabor,
> >
> > The first one works fine. Just out of curiosity, in second solution: I
dont
> > want to create a matrix. I want to add a new column to the existing
> > dataframe (i.e. V2 based on the values in V1). Is there a way to do
it?
> >
> > TIA
> > Sachin
> >
> >
> >
> > Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> >
> > Try:
> >
> > V1 <- matrix(c(10, 20, 30, 10, 10, 20), nc = 1)
> >
> > V2 <- 4 * (V1 == 10) + 6 * (V1 == 20) + 10 * (V1 == 30)
> >
> > or
> >
> > V2 <- matrix(c(4, 6, 10)[V1/10], nc = 1)
> >
> > On 4/21/06, Sachin J wrote:
> > > Hi,
> > >
> > > How can I accomplish this task in R?
> > >
> > > V1
> > > 10
> > > 20
> > > 30
> > > 10
> > > 10
> > > 20
> > >
> > > Create a new column V2 such that:
> > > If V1 = 10 then V2 = 4
> > > If V1 = 20 then V2 = 6
> > > V1 = 30 then V2 = 10
> > >
> > > So the O/P looks like this
> > >
> > > V1 V2
> > > 10 4
> > > 20 6
> > > 30 10
> > > 10 4
> > > 10 4
> > > 20 6
> > >
> > > Thanks in advance.
> > >
> > > Sachin
> > >
> > > __________________________________________________
> > >
> > >
> > >
> > > [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > 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
> > >
> >
> >
> >
> >
> > ________________________________
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