Josh Wills created DATAFU-3:
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Summary: Bootstrap sum UDF
Key: DATAFU-3
URL: https://issues.apache.org/jira/browse/DATAFU-3
Project: DataFu
Issue Type: Bug
Reporter: Josh Wills
There was a Sawzall table called bootstrapsum that I used to find handy for
some of the analysis work I did at teh goog:
http://szl.googlecode.com/svn/trunk/src/emitters/szlbootstrapsum.cc
It would be nice to have it back again in the Hadoop ecosystem. There was a
good blog post about the utility of Poisson bootstraps for random forests here:
http://blog.cloudera.com/blog/2013/02/how-to-resample-from-a-large-data-set-in-parallel-with-r-on-hadoop/
...but it's useful in all sorts of nerdy stats contexts (e.g., computing
confidence intervals for experiments.) I'm open to the particular structure of
the function; it could either have:
1) A constructor that took in the number of bootstrap samples to create and
then a call() method that took in a counting variable and a weighting variable,
or
2) Three args to the call method (num samples, counting variable, and weighting
variable, in some order.)
The return type would be a bag of tuples, (index: int, sum: T) where the type
of the sum would depend on the input type of the counting variable. index = 0
would always be the actual sum computed, while the rest of the indices would be
numbered 1..numSamples for each of the different bootstrap samples.
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