PSPP-BUG: [bug #18568] Percentile calculations are not scalable

[John Darrington]

URL:
  <http://savannah.gnu.org/bugs/?18568>

                 Summary: Percentile calculations are not scalable
                 Project: PSPP
            Submitted by: jmd
            Submitted on: Thursday 12/21/06 at 05:42
                Category: None
                Severity: 5 - Average
                  Status: None
             Assigned to: jmd
             Open/Closed: Open
         Discussion Lock: Any
                 Release: None
                  Effort: 0.00

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Details:

Percentiles as calculated by EXAMINE and FREQUENCIES use the heap to store
sorted data.  This means that failures are likely for large data sets. eg:

DATA LIST LIST /x * w *.
BEGIN DATA.
3  1
2  5000000
4  1
END DATA.

WEIGHT BY w.

EXAMINE /x
 /PERCENTILE= 10, 50, 90
 .

Internally, the data needs to be streamed into a casefile instead of an
array.




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