Displaying 1 result from an estimated 1 matches for "meanundercut".
2005 Jul 12
4
Calculation of group summaries
...I'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...