intervals

Given 2 timestamps in postgres, how do you calculate the time difference without counting whole Saturdays and Sundays? OR How do you count the number of Saturdays and Sundays in a given time interval? The following function is returning the number of full weekend days between two dates. As you need full days, you can cast the timestamps to dates before calling the function. It returns 0 in case the first date is not strictly before the second. CREATE FUNCTION count_full_weekend_days(date, date) RETURNS int AS $BODY$ SELECT ($1 < $2)::int * ( (($2 - $1) / 7) * 2 + (EXTRACT(dow FROM $1)<6 AND

I have created a data structure consisting of intervals. The data structure should naturally have an enumerator that enumerates all intervals, but I would like to expose two different enumerators that enumerate the intervals in different order. One of the enumerators enumerate the intervals really fast, but in somewhat arbitrary order. The other enumerates them in lexicographical order, but a bit slower (depends on the intervals though). Depending on what you try to achieve, one enumerator might be to prefer over the other. Is there a way to allow the user to decide which enumerator should be

I want to partition a vector (length around 10^5) into five classes. With the function classIntervals from package classInt I wanted to use style = "jenks" natural breaks but this takes an inordinate amount of time even for a much smaller vector of only 500. Setting style = "kmeans" executes almost instantaneously. library(classInt) my_n <- 100 set.seed(1) x <- mapply(rnorm, n = my_n, mean = (1:5) * 5) system.time(classIntervals(x, n = 5, style = "jenks")) R> system.time(classIntervals(x, n = 5, style = "jenks")) user system elapsed 13.46 0.00 13.45 system.time(classIntervals(x, n = 5, style =

I need to add some intervals and use the result in Excel. Since sum(time.endtime-time.starttime) returns the interval as "1 day 01:30:00" and this format breaks my Excel sheet, I thought it'd be nice to have the output like "25:30:00" but found no way to do it in the PostgreSQL documentation. Can anyone here help me out? zaratustra Since there is not an exact solution for the topic: => SELECT date_part('epoch', INTERVAL '1 day 01:30:00') * INTERVAL '1 second' hours; hours ----------- 25:30:00 (1 row) Source: Documentation The only thing I can come with (beside parsing the number of days and

I need to declare two dates in "Ymd" format: $toDate and $fromDate . $toDate represents today's date and $fromDate needs to be 4 months earlier than today. $toDate = Date('Ymd'); $fromDate = ? How do I create $fromDate ? Use the magic of strtotime : $fromDate = date("Ymd", strtotime("-4 months")); see the code below... $fourmonthsback = date("Ymd", mktime(0, 0, 0, date("m")-4, date("d"), date("Y"))); OR $fourmonthsback = mktime(0, 0, 0, date("m")-4, date("d"), date("Y")); 来源： https://stackoverflow.com/questions/4163387/how-to-subtract-4-months-from-todays-date

I have a daterange (from, to) that i want loop through an different intervals (daily, weekly, monthly, ...) How can i loop through this dateranges? Update Thanks for your answers, i came up with the following: interval = 'week' # month, year start = from while start < to stop = start.send("end_of_#{interval}") if stop > to stop = to end logger.debug "Interval from #{start.inspect} to #{stop.inspect}" start = stop.send("beginning_of_#{interval}") start += 1.send(interval) end This will loop through a date range with intervals week, month or year and respects the beginning and end of the given