R help - Apr 2012 - Assign value to new variable based on conditions on other variables

Hi Experts,

This may be simple question, I want to create new variable "seg" and
assign
values to it based on some conditions satisfied by each observation.

Here is the example:
##Below are the conditions

##if variable x2 gt 0 and x3 gt 200 then seg should take value 1, 
##if variable x2 gt 100 and x3 gt 300 then seg should take value 2
##if variable x2 gt 200 and x3 gt 400 then seg should take value 3
##if variable x2 gt 300 and x3 gt 500 then seg should take value 4

id <- c(1,2,3,4,5)
x2 <- c(200,100,400,500,600)
x3 <- c(300,400,500,600,700)
dd <- data.frame(id,x2,x3)


dd$seg[dd$x2> 0 && dd$x3> 200] <-1
dd$seg[dd$x2> 100 && dd$x3> 300] <-2
dd$seg[dd$x2> 200 && dd$x3> 400] <-3
dd$seg[dd$x2> 300 && dd$x3> 500] <-4

I tried as above but it is not working for me. What is the correct and
efficient way to do this.

Thanks for the help in advance!!


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I have got solution using within function as below

dd$Seg <- 1
dd <- within(dd, Seg[x2> 0 & x3> 200] <- 1) 
dd <- within(dd, Seg[x2> 100 & x3> 300] <- 2) 
dd <- within(dd, Seg[x2> 200 & x3> 400] <- 3) 
dd <- within(dd, Seg[x2> 300 & x3> 500] <- 4)

I sthere any better way of doing it!!

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On 10-04-2012, at 08:44, aajit75 wrote:
> Hi Experts,
> 
> This may be simple question, I want to create new variable "seg"
and assign
> values to it based on some conditions satisfied by each observation.
> 
> Here is the example:
> ##Below are the conditions
> 
> ##if variable x2 gt 0 and x3 gt 200 then seg should take value 1, 
> ##if variable x2 gt 100 and x3 gt 300 then seg should take value 2
> ##if variable x2 gt 200 and x3 gt 400 then seg should take value 3
> ##if variable x2 gt 300 and x3 gt 500 then seg should take value 4
> 
> id <- c(1,2,3,4,5)
> x2 <- c(200,100,400,500,600)
> x3 <- c(300,400,500,600,700)
> dd <- data.frame(id,x2,x3)
> 
> 
> dd$seg[dd$x2> 0 && dd$x3> 200] <-1
> dd$seg[dd$x2> 100 && dd$x3> 300] <-2
> dd$seg[dd$x2> 200 && dd$x3> 400] <-3
> dd$seg[dd$x2> 300 && dd$x3> 500] <-4

Use & (vector wise logical operation) instead of && (only works on
first element of vector)

dd$seg[dd$x2> 0 & dd$x3> 200] <-1
dd$seg[dd$x2> 100 & dd$x3> 300] <-2
dd$seg[dd$x2> 200 & dd$x3> 400] <-3
dd$seg[dd$x2> 300 & dd$x3> 500] <-4

Berend

On Apr 10, 2012, at 3:16 AM, aajit75 wrote:
> I have got solution using within function as below
>
> dd$Seg <- 1
> dd <- within(dd, Seg[x2> 0 & x3> 200] <- 1)
In this instance the first of your assignments appears superfluous.
> dd <- within(dd, Seg[x2> 100 & x3> 300] <- 2)
> dd <- within(dd, Seg[x2> 200 & x3> 400] <- 3)
> dd <- within(dd, Seg[x2> 300 & x3> 500] <- 4)
>
> I sthere any better way of doing it!!
>

dd <- with(dd, Seg <- min(findInterval(x2, c(-Inf ,100, 200, 300,  
Inf) ),
                           findInterval(x3, C(-Inf ,300, 400, 500,  
Inf) )
            )               )


David Winsemius, MD
West Hartford, CT