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  2. NaN - Wikipedia

    en.wikipedia.org/wiki/NaN

    ECMAScript (JavaScript) treats all NaN as if they are the same value. [21] Java has the same treatment "for the most part". [22] Using a limited amount of NaN representations allows the system to use other possible NaN values for non-arithmetic purposes, the most important being "NaN-boxing", i.e. using the payload for arbitrary data. [23 ...

  3. Missing data - Wikipedia

    en.wikipedia.org/wiki/Missing_data

    In the mathematical field of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points. In the comparison of two paired samples with missing data, a test statistic that uses all available data without the need for imputation is the partially overlapping samples t-test. [18]

  4. 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].

  5. Boolean data type - Wikipedia

    en.wikipedia.org/wiki/Boolean_data_type

    This approach (any value can be used as a Boolean value) was retained in most Lisp dialects (Common Lisp, Scheme, Emacs Lisp), and similar models were adopted by many scripting languages, even ones having a distinct Boolean type or Boolean values; although which values are interpreted as false and which are true vary from language to language.

  6. Python (programming language) - Wikipedia

    en.wikipedia.org/wiki/Python_(programming_language)

    The syntax :=, called the "walrus operator", was introduced in Python 3.8. It assigns values to variables as part of a larger expression. [106] In Python, == compares by value. Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c.

  7. Slowly changing dimension - Wikipedia

    en.wikipedia.org/wiki/Slowly_changing_dimension

    The null End_Date in row two indicates the current tuple version. A standardized surrogate high date (e.g. 9999-12-31) may instead be used as an end date so that null-value substitution is not required when querying. In some database software, using an artificial high date value could cause performance issues, that using a null value would prevent.

  8. Statistical data type - Wikipedia

    en.wikipedia.org/wiki/Statistical_data_type

    The following table classifies the various simple data types, associated distributions, permissible operations, etc. Regardless of the logical possible values, all of these data types are generally coded using real numbers, because the theory of random variables often explicitly assumes that they hold real numbers.

  9. Range query (database) - Wikipedia

    en.wikipedia.org/wiki/Range_query_(database)

    A range query is a common database operation that retrieves all records where some value is between an upper and lower boundary. [1] For example, list all employees with 3 to 5 years' experience. Range queries are unusual because it is not generally known in advance how many entries a range query will return, or if it will return any at all.