On Nov 13, 2009, at 6:03 AM, Jabez Wilson wrote:
Dear all, I'm trying to process a log file which logs the date, the
username and the computer number accessed. The table looks like this:
table.users
Date UserName Machine
1 2008-11-25 John 641
2 2008-11-25 Clive 611
3 2008-11-25 Jeremy 641
4 2008-11-25 Walt 722
5 2008-11-25 Tony 645
6 2008-11-26 Tony 645
7 2008-11-26 Tony 641
8 2008-11-26 Tony 641
9 2008-11-26 Walt 641
10 2008-11-26 Walt 645
11 2008-11-30 John 641
12 2008-11-30 Clive 611
13 2008-11-30 Tony 641
14 2008-11-30 John 641
15 2008-11-30 John 641
..................etc
What I want to do is to find out how many unique users logged on
each day, and how many individual machines where accessed per day.
In the above example, therefore on 2008-11-25 there were 5 separate
users accessing 4 machines, on 2008-11-26 there were 2 unique users
who used 2 machines (although both logged on more than once).
I've got as far as apply(table.users, 2, FUN=table) which gives me
an output of date, or username or machine and how many times they
were accessed, but not really what I want.
Any help appreciated
You were almost there. Just use lapply on the list object you produced:
> lapply(apply(table.users, 2, FUN=table), length)
$Date
[1] 3
$UserName
[1] 5
$Machine
[1] 4
Or if you want the individual items that you requested:
> lapply(apply(table.users, 2, FUN=table), length)$UserName
[1] 5
> lapply(apply(table.users, 2, FUN=table), length)$Machine
[1] 4
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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