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  2. pandas (software) - Wikipedia

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

    However, indices can use any NumPy data type, including floating point, timestamps, or strings. [4]: 112 Pandas' syntax for mapping index values to relevant data is the same syntax Python uses to map dictionary keys to values. For example, if s is a Series, s['a'] will return the data point at index a. Unlike dictionary keys, index values are ...

  3. Polar set - Wikipedia

    en.wikipedia.org/wiki/Polar_set

    The real polar of a subset of is the set: := { : ⁡ , } and the real prepolar of a subset of is the set: := { : ⁡ , }.. As with the absolute prepolar, the real prepolar is usually called the real polar and is also denoted by . [2] It's important to note that some authors (e.g. [Schaefer 1999]) define "polar" to mean "real polar" (rather than "absolute polar", as is done in this article) and ...

  4. Inverted index - Wikipedia

    en.wikipedia.org/wiki/Inverted_index

    The purpose of an inverted index is to allow fast full-text searches, at a cost of increased processing when a document is added to the database. [2] The inverted file may be the database file itself, rather than its index. It is the most popular data structure used in document retrieval systems, [3] used on a large scale for example in search ...

  5. Polar coordinate system - Wikipedia

    en.wikipedia.org/wiki/Polar_coordinate_system

    the point's direction from the pole relative to the direction of the polar axis, a ray drawn from the pole. The distance from the pole is called the radial coordinate, radial distance or simply radius, and the angle is called the angular coordinate, polar angle, or azimuth. [1] The pole is analogous to the origin in a Cartesian coordinate system.

  6. Reversed-phase chromatography - Wikipedia

    en.wikipedia.org/wiki/Reversed-phase_chromatography

    Reversed-phase liquid chromatography (RP-LC) is a mode of liquid chromatography in which non-polar stationary phase and polar mobile phases are used for the separation of organic compounds. [ 1 ] [ 2 ] [ 3 ] The vast majority of separations and analyses using high-performance liquid chromatography (HPLC) in recent years are done using the ...

  7. Pole and polar - Wikipedia

    en.wikipedia.org/wiki/Pole_and_polar

    If two lines a and k pass through a single point Q, then the polar q of Q joins the poles A and K of the lines a and k, respectively. The concepts of a pole and its polar line were advanced in projective geometry. For instance, the polar line can be viewed as the set of projective harmonic conjugates of a given point, the pole, with respect to ...

  8. Softmax function - Wikipedia

    en.wikipedia.org/wiki/Softmax_function

    In statistical mechanics, the softargmax function is known as the Boltzmann distribution (or Gibbs distribution): [5]: 7 the index set , …, are the microstates of the system; the inputs are the energies of that state; the denominator is known as the partition function, often denoted by Z; and the factor β is called the coldness (or ...

  9. Principal component analysis - Wikipedia

    en.wikipedia.org/wiki/Principal_component_analysis

    Principal component analysis (PCA) is a linear dimensionality reduction technique with applications in exploratory data analysis, visualization and data preprocessing.. The data is linearly transformed onto a new coordinate system such that the directions (principal components) capturing the largest variation in the data can be easily identified.