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Probabilisticdata structures. In computing, the count–min sketch (CM sketch) is a probabilistic data structure that serves as a frequency table of events in a stream of data. It uses hash functions to map events to frequencies, but unlike a hash table uses only sub-linear space, at the expense of overcounting some events due to collisions.
Median of medians. In computer science, the median of medians is an approximate median selection algorithm, frequently used to supply a good pivot for an exact selection algorithm, most commonly quickselect, that selects the k th smallest element of an initially unsorted array. Median of medians finds an approximate median in linear time.
Reservoir sampling. Reservoir sampling is a family of randomized algorithms for choosing a simple random sample, without replacement, of k items from a population of unknown size n in a single pass over the items. The size of the population n is not known to the algorithm and is typically too large for all n items to fit into main memory.
In descriptive statistics, the interquartile range (IQR) is a measure of statistical dispersion, which is the spread of the data. [ 1 ] The IQR may also be called the midspread, middle 50%, fourth spread, or H‑spread. It is defined as the difference between the 75th and 25th percentiles of the data. [ 2 ][ 3 ][ 4 ] To calculate the IQR, the ...
Streaming algorithm. In computer science, streaming algorithms are algorithms for processing data streams in which the input is presented as a sequence of items and can be examined in only a few passes, typically just one. These algorithms are designed to operate with limited memory, generally logarithmic in the size of the stream and/or in the ...
k. -nearest neighbors algorithm. In statistics, the k-nearest neighbors algorithm (k-NN) is a non-parametric supervised learning method first developed by Evelyn Fix and Joseph Hodges in 1951, [1] and later expanded by Thomas Cover. [2] It is used for classification and regression. In both cases, the input consists of the k closest training ...
In connection-oriented communication, a data stream is the transmission of a sequence of digitally encoded signals to convey information. [1] Typically, the transmitted symbols are grouped into a series of packets. [2] Data streaming has become ubiquitous. Anything transmitted over the Internet is transmitted as a data stream.
In the field of streaming algorithms, Misra–Gries summaries are used to solve the frequent elements problem in the data stream model.That is, given a long stream of input that can only be examined once (and in some arbitrary order), the Misra-Gries algorithm [1] can be used to compute which (if any) value makes up a majority of the stream, or more generally, the set of items that constitute ...