Changing data frame column headings

Can you be more explicit about your problem?

Michael,

   Data frame contains water chemistry data; site, date, parameter, value.
The column names after dcast() are, for example, alk_quant, ph_quant,
tds_quant. I wanted to remove the '_quant' from each column header.

   Using names() with a string vector of the new names did not work, so I
specified each one and names() made the changes.

Rich