[R] How to do a backward calculation for each record in a dataset

[Bert Gunter]

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-- Bert

On Sun, Feb 17, 2013 at 5:10 AM, Prakasit Singkateera
<asltjoey.rsoft at gmail.com> wrote:
> Hi Experts,
>
> I have a dataset of 3 columns:
>
> customer.name     product     cost
> John     Toothpaste     30
> Mike     Toothpaste     45
> Peter     Toothpaste     40
>
> And I have a function of cost whereby
>
> cost = 3.40 + (1.20 * no.of.orders^2)
>
> I want to do a backward calculation for each records (each customer) to
> find his no.of.orders and create a new column named "no.of.orders" in that
> dataset but I don't know how to do.
>
> Please help me.
>
> Thank you everyone,
> Prakasit
>
>         [[alternative HTML version deleted]]
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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