[R] Exclude 2014 data from mean

[Marc Schwartz]

> On Jul 31, 2015, at 1:49 PM, Adam Jauregui <adma89 at gmail.com> wrote:
> 
> Hello R-help,
> 
> I am trying to compute the mean of a quarterback's career fantasy football
> stats, but I wish to exclude his 2014 stats from the mean, as that will be
> the test data for the model I am trying to build for my academic undergrad
> research.
> 
> The code for figuring out the mean of his Yds for every career Game 1 was
> simple:
> 
> 
> *mean(brady.t$Yds[brady.t$G. == 1])*
> How can I make an "if-then" statement though so that his 2014 stats are
> excluded? Or is there an easier way besides "if-then?"
> 
> Thank you,
> 
> AKJ


It would be helpful to have a sample of data to know the structure, but take a look at:

  ?subset

for examples of more complicated logic for subsetting data frames. 

You might be able to use something along the lines of:

  mean(subset(brady.t, (G. == 1) & (Year != 2014), select = Yds)[[1]])

Basically, subset() is returning a data frame where Year does not equal 2014 and G. is equal to 1. The select argument is only returning the Yds column, which would otherwise be a list, so the [[1]] only returns a vector, which is passed to mean().

Regards,

Marc Schwartz