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  2. pandas (software) - Wikipedia

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

    Pandas (styled as pandas) is a software library written for the Python programming language for data manipulation and analysis. In particular, it offers data structures and operations for manipulating numerical tables and time series .

  3. Lift (data mining) - Wikipedia

    en.wikipedia.org/wiki/Lift_(data_mining)

    When two events are independent of each other, no rule can be drawn involving those two events. If the lift is > 1, like it is here for Rules 1 and 2, that lets us know the degree to which those two occurrences are dependent on one another, and makes those rules potentially useful for predicting the consequent in future data sets.

  4. Softmax function - Wikipedia

    en.wikipedia.org/wiki/Softmax_function

    One can normalize input scores by assuming that the sum is zero (subtract the average: where =), and then the softmax takes the hyperplane of points that sum to zero, =, to the open simplex of positive values that sum to 1 =, analogously to how the exponent takes 0 to 1, = and is positive.

  5. Feature scaling - Wikipedia

    en.wikipedia.org/wiki/Feature_scaling

    For example, many classifiers calculate the distance between two points by the Euclidean distance. If one of the features has a broad range of values, the distance will be governed by this particular feature. Therefore, the range of all features should be normalized so that each feature contributes approximately proportionately to the final ...

  6. Catastrophic cancellation - Wikipedia

    en.wikipedia.org/wiki/Catastrophic_cancellation

    In numerical analysis, catastrophic cancellation [1] [2] is the phenomenon that subtracting good approximations to two nearby numbers may yield a very bad approximation to the difference of the original numbers. For example, if there are two studs, one = long and the other = long, and they are measured with a ruler that is good only to the ...

  7. Bessel's correction - Wikipedia

    en.wikipedia.org/wiki/Bessel's_correction

    The sum of the entries in the middle column must be zero because the term a will be added across all 5 rows, which itself must equal zero. That is because a contains the 5 individual samples (left side within parentheses) which – when added – naturally have the same sum as adding 5 times the sample mean of those 5 numbers (2052).

  8. Estimation of covariance matrices - Wikipedia

    en.wikipedia.org/wiki/Estimation_of_covariance...

    Moreover, for n < p (the number of observations is less than the number of random variables) the empirical estimate of the covariance matrix becomes singular, i.e. it cannot be inverted to compute the precision matrix. As an alternative, many methods have been suggested to improve the estimation of the covariance matrix.

  9. Subtraction - Wikipedia

    en.wikipedia.org/wiki/Subtraction

    In words: the difference of two numbers is the number that gives the first one when added to the second one. Subtraction follows several important patterns. It is anticommutative, meaning that changing the order changes the sign of the answer. It is also not associative, meaning that when one subtracts more than two numbers, the order in which