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The Flajolet–Martin algorithm is an algorithm for approximating the number of distinct elements in a stream with a single pass and space-consumption logarithmic in the maximal number of possible distinct elements in the stream (the count-distinct problem).
In computer science, the count-distinct problem [1] (also known in applied mathematics as the cardinality estimation problem) is the problem of finding the number of distinct elements in a data stream with repeated elements. This is a well-known problem with numerous applications.
HyperLogLog is an algorithm for the count-distinct problem, approximating the number of distinct elements in a multiset. [1] Calculating the exact cardinality of the distinct elements of a multiset requires an amount of memory proportional to the cardinality, which is impractical for very large data sets. Probabilistic cardinality estimators ...
Elements that occur more than / times in a multiset of size may be found by a comparison-based algorithm, the Misra–Gries heavy hitters algorithm, in time (). The element distinctness problem is a special case of this problem where k = n {\displaystyle k=n} .
A direct approach to find the frequency moments requires to maintain a register m i for all distinct elements a i ∈ (1,2,3,4,...,N) which requires at least memory of order (). [3] But we have space limitations and require an algorithm that computes in much lower memory.
Get the neighboring elements of the current element; If there are no neighbors, uniquely label the current element and continue; Otherwise, find the neighbor with the smallest label and assign it to the current element; Store the equivalence between neighboring labels; On the second pass: Iterate through each element of the data by column, then ...
A function maps elements from its domain to elements in its codomain. Given a function f : X → Y {\displaystyle f\colon X\to Y} : The function is injective , or one-to-one , if each element of the codomain is mapped to by at most one element of the domain, or equivalently, if distinct elements of the domain map to distinct elements in the ...
Dataframe may refer to: A tabular data structure common to many data processing libraries: pandas (software) § DataFrames; The Dataframe API in Apache Spark;