Find timestamp difference in day in kdb

Question

How do you find the time difference in days between 2 timestamp in KDB?

For eg.

q)d1:2019.02.16D12:16:00.000
q)d2:.z.P

how to find difference between these two timestamp in days?

q)d1-d2 //in day

wpc135 · Accepted Answer · 2017-12-28T14:20:41.700

4

You can cast to the date datatype and subtract:

(`date$d1)-`date$d2

or

d1.date - d2.date

https://code.kx.com/q/ref/casting/#cast

edited Dec 28 '17 at 14:20

answered Dec 27 '17 at 18:19

wpc135

141
4

You should avoid using dot notation unless it is in a select statement. In a regular function dot notation will fail, e.g. `{x.date}.z.p`. – Thomas Smyth - Treliant Dec 27 '17 at 20:16
please replace dt.date by d2.date. – Utsav Dec 28 '17 at 06:39

score 1 · Answer 2 · answered Dec 28 '17 at 11:02

Depending on the accuracy you require you could simply do (`date$d1)-`date$d2 to check the difference of dates in days. If you are concerned with exact periods of 24 hours then the logic must be extended to include the time elements of the timestamp:

((`date$d1)-`date$d2)-0>(`time$d1)-`time$d2

Which checks to see if 24 hours have passed on the last day.

Alternatively you can compare the number of 24 hour increments in each timestamp by dividing by 1D00:00 and using floor; as in the following function:

{floor(x-y)%1D00:00}[d1;d2]

Find timestamp difference in day in kdb

2 Answers2