[R] How to....

[Jia Ying Mei]

Hi everyone,

I am not new to R, but its been over a year since I've used it, so I 
don't remember how to do some things.

I have a data set (in excel currently, but will be converted to text), 
that has date, country and price, with a price for every country for 
every date. I need to find the mean and median of the interval between 
price changes for each country and the mean and median percentage change 
for each price change within the data for a single country.

How should I go about doing this? I'd appreciate any help.

Jia Ying Mei