Describe the Enhancement

The MetOffice often defines masking regions using the mask.sid option. That defines a list of station ID names to be included in the verification region. Those station name lists are stored in a StringArray object which in turn stores them as a vector of strings. For each point observation, the PairDataPoint class checks to see if the station names appears in the specified list. However, the StringArray::has() function searches the list linearly for a match which is O(n). This task is to optimize that search to be O(log(n)):

• Add "bool Sorted" as a member of the StringArray class (mimic logic of NumArray).
• Should be false by default and reset to false by all "add" fuctions.
• Add "StringArray::sort_array()" member function (naming consistent with existing NumArray::sort_array())... which sets Sorted = true after sorting. See StackOverflow for quick/easy sorting example:

std::sort( serverList.begin() , serverList.end() )

• Enhance 2 "StringArray::has()" member function variations to check if the StringArray has already been sorted, and, if so, search more efficiently. See StackOverflow for quick/easy searching example:

std::lower_bound(serverList.begin() , serverList.end() , valuetoFind) to find first matching

• Also look at NumArray::has() and TimeArray::has()/index() to see if similar enhancements could be made for sorted arrrays.
• In config_util.cc, update the parse_sid_mask() function so that just prior to returning, call StringArray::sort(). Storing the station ID list in a sorted order should always be a good idea.
• Lastly, devise a test before/after these changes to quantify how much time is saved using this strategy. Note that this does not need to be added as a new unit test... just to quantify the improvement this work provides.

Time Estimate

2 days (?)

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Relevant Deadlines

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Funding Source

2799991

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Assignee

• Select engineer(s) or no engineer required: @sethlinden
• Select scientist(s) or no scientist required: @robdarvell (would be good for advice on testing)

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Define Related Issue(s)

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• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy
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