Steffen Müller >
Math-SZaru >
Math::SZaru::QuantileEstimator

Math::SZaru::QuantileEstimator - Quantile estimation based on Munro-Paterson algorithm

use Math::SZaru::QuantileEstimator; my $ue = Math::SZaru::QuantileEstimator->new($maxelems); $ue->add_elem("foo"); # add many more elems using add_elem ... my $inserted_elems_count = $ue->tot_elems; my $estimated_unique_count = $ue->estimate();

`Math::SZaru::QuantileEstimator`

provides a statistical estimate of quantiles in a large data set (or stream). It uses the algorithm published by Munro and Paterson: *Munro & Paterson, "Selection and Sorting with Limited Storage", Theoretical Computer Science, Vol 12, p 315-323, 1980*.

Constructor. Expects an integer indicating the number of quantiles to calculate. In a nutshell, passing 101 will mean that the return value of the `estimate`

call (see below) will return a list of min, 1st-percentile, 2nd-percentile, ..., 99th-percentile, max (min + 100 = 101). Other values cause the space between min and max to be differently divided. Asking for only two quantiles will just yield min/max to be tracked. Asking for three quantiles will add the median (50th percentile).

Given a floating point number, adds the number to the QuantileEstimator.

Same as `add_elem`

, but accepts an arbitrary list of numbers to insert into the estimator at once.

Returns the total count of the number of elements that were added to the estimator.

Returns the estimated quantiles in a raference to an array as described in the `new`

documentation above.

SZaru: "SZaru/" in llamerada.github.com

Sawzall: http://code.google.com/p/szl/

Steffen Mueller, <smueller@cpan.org>

The Perl wrapper of the SZaru library is:

Copyright (C) 2013 by Steffen Mueller

Just like SZaru itself, it is licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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