[R] How to make this for() loop memory efficient?

[Martin Morgan]

On 01/11/2012 12:09 AM, iliketurtles wrote:
> Ray, your solution works and is indeed faster than mine!
>
> It looks like it's going to take a few days to to 400,000 rows, still, which
> is unfortunate.
>
> Steve, thanks for your help, I'll definitely self-teach plyr and data.table.

I added a column with the first two digits of the module

   data$XX <- substr(L[,2], 1, 2)

then created a data frame that summarized the first module of each call 
and the length of the phone call

   df <- with(data,
              data.frame(FirstModule=tapply(XX, `phone calls`, `[[`, 1),
                         Length=tapply(XX, `phone calls`, length)))

then summarized the length of the phone calls associated with each module

   with(df, tapply(Length, FirstModule, mean))

resulting in

 > with(df, tapply(Length, FirstModule, mean))
       82       84       92       93       94       96       97
1.000000 2.000000 1.750000 1.666667 1.000000 1.222222 1.666667

Martin

>
> -----
> ----
>
> Isaac
> Research Assistant
> Quantitative Finance Faculty, UTS
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