Re: [R] A question built on How to sum one column in a data frame keyed on other columns

2009-07-04 Thread David Winsemius
On Jul 4, 2009, at 6:21 AM, Vincent Vinh-Hung wrote: Dear List: I have a question related to a previous discussion How to sum one column in a data frame keyed on other columns https://stat.ethz.ch/pipermail/r-help/2006-December/122141.html (George Nachman, Bill Venables) The original query wa

[R] A question built on How to sum one column in a data frame keyed on other columns

2009-07-04 Thread Vincent Vinh-Hung
Dear List: I have a question related to a previous discussion How to sum one column in a data frame keyed on other columns https://stat.ethz.ch/pipermail/r-help/2006-December/122141.html (George Nachman, Bill Venables) The original query was to calculate the sum of visits for each unique tuple of