Overall goal:

I'd like to have a visual representation of when certain computer applications 
are running over the course of a day (data will come from a SQL query later, 
but I'm using a csv for now). My idea is to use a gantt chart, but I'm running 
into issues with the start and end time. I'm wondering if it's because I need 
to use hours instead of days as my unit of time.

Problem #1
I'm trying to use strptime to convert a datetime string (7/12/2010  5:30:05 PM) 
to POSIX so I can use it as a start/end time in a gantt chart. ( I need to 
measure hours instead of days, so as.POSIXct/lt won't work for me. I'd also 
like to retain date info so I can create weekly/monthly averages))

When tested, I get this:

> strptime("7/12/2010 5:30:05 PM", "%X")
[1] NA

When I delete the date, I get:

> strptime("5:30:05 PM", "%X")
[1] "2010-07-30 05:30:05"

The full date string in the first example seems pretty unambiguous, so I'm not 
sure why it is not being recognized and %X should show the full datetime string 
- any suggestions?

#2
I will read the data from a csv file (and eventually, a database). A secondary 
problem I've run into is converting the entire list of times - will I need to 
create a loop to handle them all or is there a function similar to tapply() 
that I can use?

Thanks in advance for your time,

akn
                                          
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