[R] if statements on vectors

[Jim Lemon]

On 02/24/2011 08:37 PM, Dimitris Rizopoulos wrote:
> there are also vectorized logical operators; have a look at the help
> page ?'&', and try this:
>
> trend1 <- c(1,1,1,1,1,1,-1,-1,-1,-1,-1,-1)
> trend2 <- c(1,1,1,1,1,1,1,1,1,1,1,-1)
>
> position <- as.numeric((trend1 == 1 & trend2 == 1) | (trend1 == -1 &
> trend2 == -1))
> position
>
>
> I hope it helps.
>
> Best,
> Dimitris
>
How about (trend1 * trend2 + 1)/2

Jim

>
> On 2/24/2011 9:41 AM, Kushan Thakkar wrote:
>> I have two vectors: both have possible values of 1,-1, or 0
>>
>> trend1<- c(1,1,1,1,1,1,-1,-1,-1,-1,-1,-1)
>> trend2<- c(1,1,1,1,1,1,1,1,1,1,1,1,1,1,)
>>
>> i want to create a third vector that is conditional upon these two
>> vectors:
>>
>> if (trend2 == 1&& trend1 == 1) {position<- 1}
>> elseif (trend2 == -1&& trend1== -1) {position<- 1}
>> else {position<- 0}
>>
>> based on this two conditions, the position vector should have a value:
>>
>> position: 1,1,1,1,1,1,0,0,0,0,0,0
>>
>> Is there a way to do this in R without explicitly going through a for
>> loop?
>> The if condition doesn't work as it only accept one condition (aka no
>> vectors).