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  2. pandas (software) - Wikipedia

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

    As such, a DataFrame can be thought of as having two indices: one column-based and one row-based. Because column names are stored as an index, these are not required to be unique. [9]: 103–105 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 ...

  3. Data transformation (computing) - Wikipedia

    en.wikipedia.org/wiki/Data_transformation...

    Code generation is the process of generating executable code (e.g. SQL, Python, R, or other executable instructions) that will transform the data based on the desired and defined data mapping rules. [4] Typically, the data transformation technologies generate this code [5] based on the definitions or metadata defined by the developers.

  4. Pivot table - Wikipedia

    en.wikipedia.org/wiki/Pivot_table

    Column labels are used to apply a filter to one or more columns that have to be shown in the pivot table. For instance if the "Salesperson" field is dragged to this area, then the table constructed will have values from the column "Sales Person", i.e., one will have a number of columns equal to the number of "Salesperson". There will also be ...

  5. Contingency table - Wikipedia

    en.wikipedia.org/wiki/Contingency_table

    Typically, either column comparisons, which test for differences between columns and display these results using letters, or, cell comparisons, which use color or arrows to identify a cell in a table that stands out in some way. Nets or netts which are sub-totals. One or more of: percentages, row percentages, column percentages, indexes or ...

  6. Correlation - Wikipedia

    en.wikipedia.org/wiki/Correlation

    Several sets of (x, y) points, with the Pearson correlation coefficient of x and y for each set.The correlation reflects the noisiness and direction of a linear relationship (top row), but not the slope of that relationship (middle), nor many aspects of nonlinear relationships (bottom).

  7. Cook's distance - Wikipedia

    en.wikipedia.org/wiki/Cook's_distance

    In statistics, Cook's distance or Cook's D is a commonly used estimate of the influence of a data point when performing a least-squares regression analysis. [1] In a practical ordinary least squares analysis, Cook's distance can be used in several ways: to indicate influential data points that are particularly worth checking for validity; or to indicate regions of the design space where it ...

  8. 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.

  9. Hash function - Wikipedia

    en.wikipedia.org/wiki/Hash_function

    The output is a hash code used to index a hash table holding the data or records, or pointers to them. A hash function may be considered to perform three functions: Convert variable-length keys into fixed-length (usually machine-word -length or less) values, by folding them by words or other units using a parity-preserving operator like ADD or XOR,