I am using Swift 2.0+ and need it to be compatible with iOS 8.0+. I want to find out what day of the week a month starts. For example, November 15 would return Sunday, December 15 would return Tuesday, and January 16 would return Friday. I think the best approach would be to get the current day of the week and day of the month then count backwards until you reach 1 and get that day. Currently I have
// Returns the day of the week as an integer 1 being Sunday and 7 being Saturday
func dayOfWeek() -> Int {
let components = calender.component(NSCalendarUnit.Weekday, fromDate: t)
return components
}
Which calculates the current day of the week, after that I hit a roadblock.
I found the answer to be
// This function should return the value I need 0 being Sunday and 6 being Saturday
func dayMonthStarted() -> Int {
// 0 -> Sunday 6 -> Saturday
var component = calender.component(NSCalendarUnit.Day, fromDate: date)
var day = dayOfWeek()
while component > 1 {
component--
if day == 0 {
day = 6
} else {
day--
}
}
return day - 1
}
Related
Is there a Time library function or another good way to get the most recent weekday, hour, minute combination in Unix time? For example, given:
day: Monday
hour: 11
minute: 30
And it's currently Tuesday, I want the Unix time for yesterday at 11:30am. Some languages / libraries have support for thing but I cannot find something in Go that would make this easy. Any advice?
If you look at the definition of Weekday, you'll see that Sunday is 0, Monday is 1, etc. So to get to the last Monday, you have to do go back today-Monday, and move back to 11:30 that day. However, this doesn't work if it is already Monday and before 11:30, so you need to check for that:
now:=time.Now()
dayOffset:=now.Weekday()-time.Monday
targetDate:=now.AddDate(0,0,-int(dayOffset))
targetDate=time.Date(targetDate.Year(),targetDate.Month(),targetDate.Day(),11,30,0,0,targetDate.Location())
if targetDate.After(now) {
targetDate=targetDate.AddDate(0,0,-7)
}
My attempt at a simple and intuitive solution. See code comments for explanation
package main
import (
"fmt"
"time"
)
func main() {
// The target day / hour / minute
const (
day = time.Monday
hour = 21
minute = 0
)
// The starting time to work from
startTime := time.Now()
// Create the time on that day with the desired hour and minute
t := time.Date(startTime.Year(), startTime.Month(), startTime.Day(), hour, minute, 0, 0, startTime.Location())
// As long as we're on the wrong weekday, or not before the start time, back up one day
for t.Weekday() != day || !t.Before(startTime){
t = t.AddDate(0, 0, -1)
}
// Print the time, and it's Unix timestamp.
fmt.Println(t, t.Unix())
}
Is there anything like the Oracle "NEXT_DAY" function available in the syntax that Crystal Reports uses?
I'm trying to write a formula to output the following Monday # 9:00am if the datetime tested falls between Friday # 9:00pm and Monday # 9:00am.
So far I have
IF DAYOFWEEK ({DATETIMEFROMMYDB}) IN [7,1]
OR (DAYOFWEEK({DATETIMEFROMMYDB}) = 6 AND TIME({DATETIMEFROMMYDB}) in time(21,00,00) to time(23,59,59))
OR (DAYOFWEEK({DATETIMEFROMMYDB}) = 2 AND TIME({DATETIMEFROMMYDB}) in time(00,00,00) to time(08,59,59))
THEN ...
I know I can write seperate IF statements to do a different amount of DateAdd for each of Fri, Sat, Sun, Mon, but if I can keep it concise by lumping all of these into one I would much prefer it. I'm already going to be adding additional rules for if the datetime falls outside of business hours on the other weekdays so I want to do as much as possible to prevent this from becoming a very overgrown and ugly formula.
Since there is no CR equivalent that I know of, you can just cheat and borrow the NEXT_DAY() function from the Oracle database. You can do this by creating a SQL Expression and then entering something like:
-- SQL Expression {%NextDay}
(SELECT NEXT_DAY("MYTABLE"."MYDATETIME", 'MONDAY')
FROM DUAL)
then you could either use that directly in your formula:
IF DAYOFWEEK ({MYTABLE.MYDATETIME}) IN [7,1]
OR (DAYOFWEEK({MYTABLE.MYDATETIME}) = 6 AND TIME({MYTABLE.MYDATETIME}) in time(21,00,00) to time(23,59,59))
OR (DAYOFWEEK({MYTABLE.MYDATETIME}) = 2 AND TIME({MYTABLE.MYDATETIME) in time(00,00,00) to time(08,59,59))
THEN DateTime(date({%NextDay}),time(09,00,00))
Or, the even better way would be to just stuff ALL of the logic into the SQL Expression and do away with the formula altogether.
Considering Sunday is 1
And the first 7 is the week we want to back
7 = 1 week
14 = 2 weeks
The last Number (1) is 1 for Sunday, 2 for Monday, 3 for Tuestday
Last Sunday 1 week ago
Today - 7 + ( 7 - WEEKDAY(TODAY) )+1
Last Monday 2 weeks ago
Today - 14 + ( 7 - WEEKDAY(TODAY) )+2
So this 2 formulas give me MONDAY LAST WEEK and SUNDAY LAST WEEK.
EvaluateAfter({DATETIMEFROMMYDB}) ;
If DayOfWeek ({DATETIMEFROMMYDB}) In [crFriday,crSaturday,crSunday,crMonday]
then
IF DayOfWeek ({DATETIMEFROMMYDB}) In [crFriday]
AND TIME({DATETIMEFROMMYDB}) >= time(21,00,00)
then //your code here
Else if Not(DayOfWeek ({DATETIMEFROMMYDB}) In [crFriday] )
AND (TIME({DATETIMEFROMMYDB}) >= time(00,00,00) AND TIME({DATETIMEFROMMYDB}) <= time(23,59,59))
then //your code here
Else if DayOfWeek ({DATETIMEFROMMYDB})In [crMonday]
AND TIME({DATETIMEFROMMYDB}) < time(09,00,00)
then //your code here
I need to build a Linq query that will show the results as follow:
Data:
Sales Month
----------------------
10 January
20 February
30 March
40 April
50 May
60 June
70 July
80 August
90 September
100 October
110 November
120 December
I need to get the results based on this scenario:
month x = month x + previous month
that will result in:
Sales Month
--------------------
10 January
30 February (30 = February 20 + January 10)
60 March (60 = March 30 + February 30)
100 April (100 = April 40 + March 60)
.........
Any help how to build this query ?
Thanks a lot!
Since you wanted it in LINQ...
void Main()
{
List<SaleCount> sales = new List<SaleCount>() {
new SaleCount() { Sales = 10, Month = 1 },
new SaleCount() { Sales = 20, Month = 2 },
new SaleCount() { Sales = 30, Month = 3 },
new SaleCount() { Sales = 40, Month = 4 },
...
};
var query = sales.Select ((s, i) => new
{
CurrentMonth = s.Month,
CurrentAndPreviousSales = s.Sales + sales.Take(i).Sum(sa => sa.Sales)
});
}
public class SaleCount
{
public int Sales { get; set; }
public int Month { get; set; }
}
...but in my opinion, this is a case where coming up with some fancy LINQ isn't going to be as clear as just writing out the code that the LINQ query is going to generate. This also doesn't scale. For example, including multiple years worth of data gets even more hairy when it wouldn't have to if it was just written out the "old fashioned way".
If you don't want add up all of the previous sales for each month, you will have to keep track of the total sales somehow. The Aggregate function works okay for this because we can build a list and use its last element as the current total for calculating the next element.
var sales = Enumerable.Range(1,12).Select(x => x * 10).ToList();
var sums = sales.Aggregate(new List<int>(), (list, sale) => list.Concat(new List<int>{list.LastOrDefault() + sale});
I can only find algorithm for getting ISO 8601 week (week starts on a Monday).
However, the iCal spec says
A week is defined as a seven day period, starting on the day of the
week defined to be the week start (see WKST). Week number one of the
calendar year is the first week that contains at least four (4) days
in that calendar year.
Therefore, it is more complex than ISO 8601 since the start of week can be any day of the week.
Is there an algorithm to determine what is the week number of a date, with a custom start day of week?
or... is there a function in iCal4j that does this? Determine a weekno from a date?
Thanks!
p.s. Limitation: I'm using a JVM language that cannot extend a Java class, but I can invoke Java methods or instantiate Java classes.
if (input_date < firstDateOfTheYear(WKST, year))
{
return ((isLeapYear(year-1))?53:52);
}
else
{
return ((dayOfYear(input_date) - firstDateOfTheYear(WKST, year).day)/7 + 1);
}
firstDateOfTheYear returns the first calendar date given a start of week(WKST) and the year, e.g. if WKST = Thursday, year = 2012, then it returns Jan 5th.
dayOfYear returns sequencial numerical day of the year, e.g. Feb 1st = 32
Example #1: Jan 18th, 2012, start of week is Monday
dayOfYear(Jan 18th, 2012) = 18
firstDateOfTheYear(Monday, 2012) = Jan 2nd, 2012
(18 - 2)/7 + 1 = 3
Answer Week no. 3
Example #2: Jan 18th, 2012, start of week is Thursday
dayOfYear(Jan 18th, 2012) = 18
firstDateOfTheYear(Thursday, 2012) = Jan 5th, 2012
(18 - 5)/7 + 1 = 2
Answer Week no. 2
Example #3: Jan 1st, 2012, start of week is Monday
firstDateOfTheYear(Monday, 2012) = Jan 2nd, 2012
IsLeapYear(2012-1) = false
Jan 1st, 2012 < Jan 2nd, 2012
Answer Week no. 52
Let daysInFirstWeek be the number of days on the first week of the year that are in January. Week starts on a WKST day. (e.g. if Jan 1st is a WKST day, return 7)
Set dayOfYear to the n-th days of the input date's year (e.g. Feb 1st = 32)
If dayOfYear is less than or equal to daysInFirstWeek
3.1. if daysInFirstWeek is greater than or equal to 4, weekNo is 1, skip to step 5.
3.2. Let daysInFirstWeekOfLastYear be the number of days on the first week of the previous year that are in January. Week starts on a WKST day.
3.3. if daysInFirstWeekOfLastYear is 4 or last year is Leap year and daysInFirstWeekOfLastYear is 5, weekNo is 53, otherwise weekNo is 52, skip to step 5.
Set weekNo to ceiling((dayOfYear - daysInFirstWeek) / 7)
4.1. if daysInFirstWeek greater than or equal to 4, increment weekNo by 1
4.2. if daysInFirstWeek equal 53 and count of days on the first week (starting from WKST) of January in the year of inputDate's year + 1 is greater than or equal to 4, set weekNo to 1
return weekNo
Would anyone know why the following code works correctly on Windows and not on Mac??
Today (24/11/2010) should return 47 not 48 as per MacOS
def fm_date = '24/11/2010'
import java.text.SimpleDateFormat
def lPad = {it ->
st = '00' + it.toString()
return st.substring(st.length()-2, st.length())
}
dfm = new SimpleDateFormat("dd/MM/yyyy")
cal=Calendar.getInstance()
cal.setTime( dfm.parse(fm_date) )
now = cal.get(Calendar.WEEK_OF_YEAR)
cal.add(Calendar.DAY_OF_MONTH,-7)
prev = cal.get(Calendar.WEEK_OF_YEAR)
cal.add(Calendar.DAY_OF_MONTH,14)
next = cal.get(Calendar.WEEK_OF_YEAR)
prev = 'diary' + lPad(prev) + '.shtml'
next = 'diary' + lPad(next) + '.shtml'
return 'diary' + lPad(now) + '.shtml'
I believe it's an ISO week number issue...
If I use this code adapted (and groovyfied) from yours:
import java.text.SimpleDateFormat
def fm_date = '24/11/2010'
Calendar.getInstance().with { cal ->
// We want ISO Week numbers
cal.firstDayOfWeek = MONDAY
cal.minimalDaysInFirstWeek = 4
setTime new SimpleDateFormat( 'dd/MM/yyyy' ).parse( fm_date )
now = cal[ WEEK_OF_YEAR ]
}
"diary${"$now".padLeft( 2, '0' )}.shtml"
I get diary47.shtml returned
As the documentation for GregorianCalendar explains, if you want ISO Month numbers:
Values calculated for the WEEK_OF_YEAR
field range from 1 to 53. Week 1 for a
year is the earliest seven day period
starting on getFirstDayOfWeek() that
contains at least
getMinimalDaysInFirstWeek() days from
that year. It thus depends on the
values of getMinimalDaysInFirstWeek(),
getFirstDayOfWeek(), and the day of
the week of January 1. Weeks between
week 1 of one year and week 1 of the
following year are numbered
sequentially from 2 to 52 or 53 (as
needed).
For example, January 1, 1998 was a
Thursday. If getFirstDayOfWeek() is
MONDAY and getMinimalDaysInFirstWeek()
is 4 (these are the values reflecting
ISO 8601 and many national standards),
then week 1 of 1998 starts on December
29, 1997, and ends on January 4, 1998.
If, however, getFirstDayOfWeek() is
SUNDAY, then week 1 of 1998 starts on
January 4, 1998, and ends on January
10, 1998; the first three days of 1998
then are part of week 53 of 1997.
Edit
Even Groovier (from John's comment)
def fm_date = '24/11/2010'
Calendar.getInstance().with { cal ->
// We want ISO Week numbers
cal.firstDayOfWeek = MONDAY
cal.minimalDaysInFirstWeek = 4
cal.time = Date.parse( 'dd/MM/yyyy', fm_date )
now = cal[ WEEK_OF_YEAR ]
}
"diary${"$now".padLeft( 2, '0' )}.shtml"
Edit2
Just ran this on Windows using VirtualBox, and got the same result