need more help.... Re: iterating over a data frame the R way?
On Jan 1, 2010, at 11:20 AM, donahchoo at me.com wrote:
Okay, I don't know if I'm blocking because of my other programming language experience of if I'm just being dense. I have a data.frame with high,open,low,last,day, and start_time time columns. What I want to do is get all the rows with the same day and process each of those columns.
The usual method of doing that sort of operation the application of a function within categories using tapply. See the examples in: ?tapply
If I was able to run a query against the data.frame I would be want something like: result = all the rows where the day is equal to 2007-12-05 Then I would want get max(result["high"]), min(result["low"]) How do I do this? I tired sqldf, but its complaining about libtcl0.5.8 not being found. I'm on OS X 10.5.8 and haven't yet tired to install a new version of tcl in /usr/local. Here's the dataframe:
Nope... nothing came through. Read the posting guide for the proper way to either include r objects in an email or to attache txt files. David Winsemius, MD Heritage Laboratories West Hartford, CT