[R] Elegant way to transform dataframe?

[Barry Rountree]

Hello,

I have a dataframe with columns like:

  parameter1 parameter2 metricname value

and I'd like to transform it into a dataframe with columns:

  parameter1 parameter2 metric1 metric2 metric3

where the values for each metric would be in the appropriate column.  There are often multiple values for a given (parameter1, parameter2, metricname) triple.  In this case, I want to use the minimum value.

A constant number of metrics is associated with each possible combination of parameters.

I've cobbled together code that performs this using nested loops and far too many variables.  The number of metrics has now gone up by an order of magnitude and I'm looking for a more elegant way of doing this.  

If anyone has a short bit of code that can deal with this, I'd really appreciate having a look.

Thanks much,

Barry