[R-Forge #2341] Auto setkey when worth it
Nobody has claimed this yet.
Assessment
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Newbie friendliness
- 25/100
- Issue type
- Feature
- Clarity
- Needs clarification
- Activity status
- Stale
- Tech stack
- r
- Domain
- performance
Research direction
Start by reproducing the X[X], X[X,mult="first"], and X[Y] examples with verbose=TRUE, then investigate the binary-search and sequencing timings noted in the issue. The work is done when a clear criterion for automatically setting a key or detecting inefficient search progress is established and covered by performance checks.
Written by the indexing model from the issue text.
Description
Submitted by: Matt Dowle; Assigned to: Nobody; R-Forge link
Or auto detect when binary search is progressing.
X = CJ(a=seq_len(2e3),b=seq_len(1e3))
Y = expand.grid(a=seq_len(6e3),b=seq_len(1e3)) # not in group order (as out of order you could get)
system.time(X[X,verbose=TRUE])
Starting binary search ...done in 0.958 secs
user system elapsed
1.000 0.016 1.020
system.time(X[X,mult="first",verbose=TRUE])
Starting binary search ...done in 0.959 secs
user system elapsed
1.228 0.028 1.260
system.time(X[Y,verbose=TRUE]) # very slow as well. 2 columns in key, very out of order (hugely page inefficient)
Starting binary search ...done in 4.74 secs
user system elapsed
7.932 0.452 8.424
# not sure if binary search or the seq() afterwards. TO DO: investigate (add timing of binary search)
system.time(X[Y,mult="first",verbose=TRUE])
Starting binary search ...done in 4.731 secs
user system elapsed
8.461 0.388 8.875
- Dominant language
- R
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- Merged PRs (30d)
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Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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