SPOP key [count]

Removes and returns one or more random members from the set value store at key.

This operation is similar to SRANDMEMBER, that returns one or more random elements from a set but does not remove it.

By default, the command pops a single member from the set. When provided with the optional count argument, the reply will consist of up to count members, depending on the set's cardinality.

*Return value

When called without the count argument:

Bulk string reply: the removed member, or nil when key does not exist.

When called with the count argument:

Array reply: the removed members, or an empty array when key does not exist.

*History

  • >= 3.2: Added the count argument.

*Examples

redis>  SADD myset "one"
(integer) 1
redis>  SADD myset "two"
(integer) 1
redis>  SADD myset "three"
(integer) 1
redis>  SPOP myset
"two"
redis>  SMEMBERS myset
1) "three"
2) "one"
redis>  SADD myset "four"
(integer) 1
redis>  SADD myset "five"
(integer) 1
redis>  SPOP myset 3
1) "four"
2) "five"
3) "one"
redis>  SMEMBERS myset
1) "three"
redis> 

*Distribution of returned elements

Note that this command is not suitable when you need a guaranteed uniform distribution of the returned elements. For more information about the algorithms used for SPOP, look up both the Knuth sampling and Floyd sampling algorithms.