Time in Splus

12/02/2004

It has been a while since writing the previous post. Most of my ‘web time’ has been devoted to put together the Forestry in Tasmania site (where I am still doing some work). Anyway, malady this week I imported an Excel spreadsheet into Splus, where I had defined a few columns as time. I usually do not use time formats in Excel, but this was not my project and I needed the times in Splus. Surprise! All times were there, but with weird dates attached. Then I tried importing dates and, surprise again, dates had this 00:00:00 attached. To be more precise, only the time showed in the column when using the data viewer.

A few visits to the online language reference and to the discussion group archives where useful. Times and dates are stored using the timeDate class, and it is possible to query the variable containing time and date using the functions: hours, minutes and seconds for time, and days, weekdays, months, quarters, years, and yeardays (which gives the number of day within a year) for dates. These functions return vectors. In addition, it is possible to create data frames where each column contains an integer with the following functions: hms (hour, minutes and seconds), mdy (month, day and year) and wdydy (weekday, yearday and year).

timeDate can also be used to transform strings to objects of class timeDate. For example:

x <- timeDate(c("1/1/1998 3:05:23.4",
"5/10/2005 2:15:11.234 PM"))

which then can be queried as:

mdy(x)
hms(x)
wdydy(x)
hours(x)
etc
Filed in programming, statistics

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