Differences between adjacent list items

deltas x    deltas[x]

Where x is a numeric or temporal vector, returns differences between consecutive pairs of its items.

q)deltas 1 4 9 16
1 3 5 7

In a query to get price movements:

update diff:deltas price by sym from trade

With signum to count the number of up/down/same ticks:

q)select count i by signum deltas price from trade
price| x
-----| ----
-1   | 247
0    | 3
1    | 252