[R] Merging daily and weekly data

[Øystein Myrland]

Dear R-help group,

I have a dataset with daily closing prices from a stock exchange (consecutive 5 trading days) from a firm trading a specific commodity. The date variable looks like:

quote_date
20080411

With the format; yyyymmdd.

Moreover, I have another data set with a (average) weekly price of the underlying commodity. The date variables in this dataset are only year and a week number.

I would like to calculate a common date number or ID based on week number that enables me to merge these two datasets, so that it looks like this: 

quote_date	year	week	week.price
20080407	2008	15	27.45 
20080408	2008	15	27.45
20080409	2008	15	27.45
20080410	2008	15	27.45
20080411	2008	15	27.45

The weekly price is constant for the 5 trading days in the daily file. Any good suggestions on how to do this?

All the best,
Oystein