On 07/31/2010 03:12 AM, Andrew Noyes wrote:
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
try this:
strptime("7/12/2010 5:30:05 PM", "%d/%m/%Y %I:%M:%S %p")
When I delete the date, I get:
strptime("5:30:05 PM", "%X")
[1] "2010-07-30 05:30:05"
%X only specifies time
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?
Just pass the whole vector of dates as character strings - you'll get a
vector of date/time values.
Jim
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