[R] how to read data from table based a condition

[Uwe Ligges]

Marc Moragues wrote:
> 
> Xin <jasonshi510 <at> hotmail.com> writes:
> 
> 
>> y<-data[,7]
>> x<-data[,3]
>>
>> I want to know the mean of y if corresponding x=1.
>>
> 
> Try this:
> 
> mean(data[data[,3]==1,data[,7])


Folks, please!

1. If you answer, please write at least syntactically valid code (look 
at your index brackets).

Just
   mean(y[x==1])
should do the trick....


2. It is a bad idea to do others' homeworks, they won't learn much this way.


Best wishes,
Uwe Ligges





> You can also look at ?subset.
> 
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