search for: nundercut

Displaying 1 result from an estimated 1 matches for "nundercut".

Did you mean: undercut
2005 Jul 12
4
Calculation of group summaries
...#39;d like to do something slightly more complex, using a data frame and groups identified by unique combinations of three id variables. There may be thousands of such combinations in the data. This is easy in SQL: select year, site_id, visit_no, mean(undercut) AS meanUndercut, count(undercut) AS nUndercut, std(undercut) AS stdUndercut from channelMorphology group by year, site_id, visit_no ; Reading a CSV written by SAS and selecting only records expected to have values is also straight forward in R, but getting those summary values for each...