Jure Leskovec, Stanford University - SNAP - Stanford University

Filtering a stream:
Select elements with
property x from stream
Bloom filters
Counting distinct elements:
Number of distinct elements in
the last k elements of the stream
Flajolet-Martin:
Item
hash
func h
0010001011000
Drop the item
For each item a, let r(a) be the # of trailing 0s in h(a)
Record R = the maximum r(a) seen
R = max a r(a), over all the items a seen so far
Estimated number of distinct elements = 2 R
Output the
item since it
may be in S;
Bit
array B
3/9/2011 Jure Leskovec, Stanford C246: Mining Massive Datasets 34