top

Operator

  top — get top N sorted values of input sequence

Synopsis

top <const-expr> <expr> [, <expr> ...]

Description

The top operator returns the top N values from a sequence sorted in descending order by one or more expressions. N is given by <const-expr>, a compile-time constant expression that evaluates to a positive integer.

top is functionally similar to sort but is less resource intensive because only the top N values are stored in memory (i.e., values less than the minimum are discarded).

Examples

Grab the top two values from a sequence of integers

echo '1 5 3 9 23 7' | zq -z 'top 2 this' -

=>

23
9

Find the two names most frequently referenced in a sequence of records

echo '{name:"joe", age:22} {name:"bob", age:37} {name:"liz", age:25}
      {name:"bob", age:18} {name:"liz", age:34} {name:"zoe", age:55}
      {name:"ray", age:44} {name:"sue", age:41} {name:"liz", age:60}' |
  zq -z 'count() by name | top 2 count' -

=>

{name:"liz",count:3(uint64)}
{name:"bob",count:2(uint64)}