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

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Math-SZaru-0.01.tar.gz

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NAME ^

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

SYNOPSIS ^

  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();

DESCRIPTION ^

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.

METHODS ^

new

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).

add_elem

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

add_elems

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

tot_elems

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

estimate

Returns the estimated quantiles in a raference to an array as described in the new documentation above.

SEE ALSO ^

Math::SZaru

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

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

AUTHOR ^

Steffen Mueller, <smueller@cpan.org>

COPYRIGHT AND LICENSE ^

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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