I'm a beginner to KDB/Q Langage, and I'm looking to find a way to convert a date object (or its string representation) to the format MM/DD. For example, I have 2016-09-23 and I would like to format it to 09/23.
There is another thread relating to this subject, but I am not sure how helpful it'd be : How to produce a formatted date string in Q/KDB?
In Q Language, is there any function similar to the ones like convert(varchar, getdate(), 112) in SQL?
No such convert function exists in Kdb+ - but you convert it yourself with some basic string manipulation in Kdb - an example:
q) show dt:.z.d
2016.09.26
q)"/" sv 1 _ "." vs string dt
"09/26"
See vs(vector from scalar) and sv (scalar from vector) for more information on splitting / joining a string.
The code above also uses _(drop) to drop the first portion (year) of the date after the sting has been split by "."
If your strings are in a standard format (i.e YYYY-MM-DD), it will be quicker to use indexing @ depth.
q)list:("2016-09-23";"2016-10-23")
q)5_'.[list;(::;4 7);:;"/"]
"09/23"
"10/23"
For a very large vector, and provided you're not set on using a "/", this will be pretty fast:
q)dts:.z.d+til 1000000;
q)string[dts][;8 9 4 5 6]
"29.06"
"30.06"
"01.07"
"02.07"
If you want the "/":
"/"^string[dts][;8 9 10 5 6]
Misread the question; this is for DD/MM format.
Check out this GitHub library for datetime formatting. It supports the excel way of formatting date and time. Though it might not be the right fit for formatting a very large number of objects.
q).dtf.format["mm/dd"; 2016.09.23]
"09/23"
q).dtf.format["yy/m/d"; 2016.09.03] // another example
"16/9/3"
