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  2. Missing data - Wikipedia

    en.wikipedia.org/wiki/Missing_data

    The expectation-maximization algorithm is an approach in which values of the statistics which would be computed if a complete dataset were available are estimated (imputed), taking into account the pattern of missing data. In this approach, values for individual missing data-items are not usually imputed.

  3. NaN - Wikipedia

    en.wikipedia.org/wiki/NaN

    In computing, NaN (/ n æ n /), standing for Not a Number, is a particular value of a numeric data type (often a floating-point number) which is undefined as a number, such as the result of 0/0. Systematic use of NaNs was introduced by the IEEE 754 floating-point standard in 1985, along with the representation of other non-finite quantities ...

  4. Dataframe - Wikipedia

    en.wikipedia.org/wiki/Dataframe

    Dataframe may refer to: A tabular data structure common to many data processing libraries: pandas (software) § DataFrames; The Dataframe API in Apache Spark; Data frames in the R programming language; Frame (networking)

  5. pandas (software) - Wikipedia

    en.wikipedia.org/wiki/Pandas_(software)

    If data is a Series, then data['a'] returns all values with the index value of a. However, if data is a DataFrame, then data['a'] returns all values in the column(s) named a. To avoid this ambiguity, Pandas supports the syntax data.loc['a'] as an alternative way to filter using the index.

  6. Null (SQL) - Wikipedia

    en.wikipedia.org/wiki/Null_(SQL)

    These mistakes are usually the result of confusion between Null and either 0 (zero) or an empty string (a string value with a length of zero, represented in SQL as ''). Null is defined by the SQL standard as different from both an empty string and the numerical value 0, however. While Null indicates the absence of any value, the empty string ...

  7. Gaussian elimination - Wikipedia

    en.wikipedia.org/wiki/Gaussian_elimination

    Moreover, Hadamard's inequality provides an upper bound on the absolute values of the intermediate and final entries, and thus a bit complexity of ~ (), using soft O notation. Moreover, as an upper bound on the size of final entries is known, a complexity O ~ ( n 4 ) {\displaystyle {\tilde {O}}(n^{4})} can be obtained with modular computation ...

  8. Feature scaling - Wikipedia

    en.wikipedia.org/wiki/Feature_scaling

    Selecting the target range depends on the nature of the data. The general formula for a min-max of [0, 1] is given as: [3] ′ = () where is an original value, ′ is the normalized value. For example, suppose that we have the students' weight data, and the students' weights span [160 pounds, 200 pounds].

  9. Frame (artificial intelligence) - Wikipedia

    en.wikipedia.org/wiki/Frame_(artificial...

    Their value might change with the new information encountered. Different frames may share the same terminals. Each piece of information about a particular frame is held in a slot. The information can contain: Facts or Data Values (called facets) Procedures (also called procedural attachments) IF-NEEDED: deferred evaluation