Optimize value_counts function for performance improvement with missing classes #1073
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Summary
This PR partially addresses #862
[ ✏️ Write your summary here. ]
While working on token_classification I noticed when I worked with batches the value_counts function was around the top 30 when profiling. By preallocating the array and given that np.unique returns a sorted array, we can avoid the creation of multiple lists before converting them into an array which is orders of magnitude faster. With this PR almost all the time is spent in the np.unique function. The improvement is only noticeable when all the classes are not present (mostly batches with a relative high number of classes).
For memory I used the memory-profiler library. The code I used for benchmarking is copied below. In addition I sorted the imports in the modified files.
Code Setup
Note: when calling value_counts on x I measured memory only once after the timeit function. Otherwise it would print too many statements.
Current version
This PR
Testing
References
Reviewer Notes