Hi Ric,
After reading your email this morning, I went and check how I actually used
dates in J. Please keep in mind that I primarily read and save data to and from
MS-SQL Servers. The front end system is using C# or VB.NET (depending on the
project tech lead) so the data is read into .NET to DataTable.
To import a DataTime object from a DataTable to J, I actually convert this
first into a string in this format: MM/DD/YYYY HH:MM:SS.MS
<lang C#>
string objTemp = value.Month.ToString() + "/" + value.Day.ToString() + "/"
+ value.Year.ToString();
objTemp += " " + value.Hour.ToString() + ":" + value.Minute.ToString() +
":" + value.Second.ToString();
objTemp += "." + value.Millisecond.ToString();
</lang>
I then send this new string to J using J's setB() method. Then I convert this
to a proper number as YYYYMMDD.timeofday like so:
[dtemp=. 6!:0 ''
2009 9 10 11 21 20.526
[ddate=. 10000 100 100 #. 3 {. dtemp
20090910
[dtime=. 0.00001 * 100000 * (24 60 60 #. 3 }.dtemp) % 86400
0.473154236111111
[ndate=. ddate + dtime
20090910.4731542
Of course, after a few operations, I have to save this back to MS-SQL by
creating an SQL DML command (INSERT or UPDATE) but have to convert this to the
original date and time format first.
First off, it's simple enough to get this data back to the J date format:
[vdate=. 10000 100 100 #: <. ndate
2009 9 10
[vtime=. 24 60 60 #: 0.00001 * (<....@+&0.5) 100000 * ndate * 86400
11 21 20.52587890625
vdate, vtime
2009 9 10 11 21 20.52587890625
The resulting data can now be easily converted back to MM/DD/YYYY HH:MM:SS.MS
which is required by SQL.
To support this concept of date and time, I actually made the following verbs:
NB. =========================================================
NB.*dateplus (a) Adds day and fractional time to a date
NB.
NB. x is calendar date
NB. y is day and fractional time
NB. returns calendar date in YYYYMMDD.fractional time
NB. =========================================================
NB.*dateminus (a) Subtracts a day and fractional time to a date
NB.
NB. x is calendar date
NB. y is day and fractional time
NB. returns calendar date in YYYYMMDD.fractional time
NB. =========================================================
NB.*dateminusdate (a) Subtracts two dates and returns days and fractional time
NB.
NB. x is calendar date
NB. y is calendar date
NB. returns days and fractional time
I apologize for not posting the actual code since I heavily use the
"Primitives" and my own library ... hmmm ... to give you an idea, dateplus
actually looks like this:
NB. =========================================================
NB.*dateplus (a) Adds day and fractional time to a date
NB.
NB. x is calendar date
NB. y is day and fractional time
NB. returns calendar date in YYYYMMDD.fractional time
dateplus=: dyad define
NB. Get the date and time
date=. rounddown x
time=. decimal x
ndate=. rounddown y
ntime=. decimal y
NB. Start by adding the time, this to make sure we handle
NB. extra days
time=. time plus ntime
ndate=. ndate plus rounddown time
time=. decimal time
NB. Now we calculate the actual date and return it in YYYYMMDD.time
(1 todate (1 todayno date) + ndate) + time
)
I heavily use this concept of Date and Time and the support verbs for my
Production Planning System which looks similar to MS-Project with its drag and
drop Gantt chart bars. I use GDI+ in .NET for drawing the Gantt chart and all
processing is done in J using a customized library based on the .NET interface
that can be found here: http://www.jsoftware.com/jwiki/Guides/J%20VB.NET
Wow, my email is long again. To summarize, in my use of J and datetime datatype
... I found out that I only need three manipulation verbs which are dateplus,
dateminus, dateminusdate. I also find the native array as a datetime format
quite inconvenient and has to atomize it into a YYYYMMDD.timefraction format.
I hope this helps in any way with what you want to do. :)
r/Alex
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Sherlock, Ric
Sent: Thursday, September 10, 2009 9:08 AM
To: Programming forum
Subject: [Jprogramming] Extending dates.ijs
Hi all,
Raul's recent request for extending getdate from the dates.ijs script, got me
thinking about my "wishlist" for handling dates as well as past forum
discussions suggesting extensions.
I wonder if we (the J community) put our collective heads together, whether we
can come up with something more generally useful than the individual efforts
that I'm sure we currently all have tucked away.
Some of the ideas that I've collated so far are:
* extend existing verbs to handle times as well as dates
* more flexible formatting of date & time string representations
* time-zone conversion?
I've set up a page on the wiki to act as a focus for the project:
http://www.jsoftware.com/jwiki/RicSherlock/Extend%20Dates%20Project
Any and all ideas/comments/offers of help/suggestions are solicited!!
Ric
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