Reply To: How can I apply a func to a grouped table?

[rocuinneagain]

In my answer I use 0N which is the long null. If your table column type for AskOrder is float then the resulting column will be of mixed type. Check by calling meta on the result. save cannot write mixed type columns like this.

A good solution is to update f to ensure it uses a null of the correct datatype:

f:{i:az -1+(where deltas y xrank az:asc z),count z;(`$x,/:string 1+til y)!i,(y-count i)#z count z}

The added bit is z count z in place of 0N

Indexing out of bounds on a q vector returns nulls of the dataype of the vector:

q)(0 1)2 / Long null returned
0N
q)(0 1f)2 / Float null returned
0n