Improve efficiency of variable matching

[sbfnk]

Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

Improve the efficiency of variable matching to fix #735. This is done by first checking for exact matches and removing any matches from the following loop.

As far as I can tell this retains the exact same functionality. The example in #735 runs in under 10s vs. >2mins before. All relevant tests seem to pass.

Copyright and Licensing

Sebastian Funk

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[codecov-commenter]

Codecov Report

Merging #736 (fba4bef) into master (b5d3a77) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #736      +/-   ##
==========================================
- Coverage   88.29%   88.28%   -0.02%     
==========================================
  Files          12       12              
  Lines        4075     4071       -4     
==========================================
- Hits         3598     3594       -4     
  Misses        477      477              

Impacted Files	Coverage Δ
R/csv.R	96.42% <100.00%> (-0.02%)	⬇️
R/utils.R	74.01% <100.00%> (-0.12%)	⬇️

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[rok-cesnovar]

Great stuff! Thanks a lot.

[jgabry]

Awesome, thank you!