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Outdated suggestions cannot be applied.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.
โก Bolt: Optimize dataframe subset modifications #180
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. Weโll occasionally send you account related emails.
Already on GitHub? Sign in to your account
base: master
Are you sure you want to change the base?
โก Bolt: Optimize dataframe subset modifications #180
Changes from all commits
230605cc2b6bd5230fd7458b828bFile filter
Filter by extension
Conversations
Uh oh!
There was an error while loading. Please reload this page.
Jump to
Uh oh!
There was an error while loading. Please reload this page.
There are no files selected for viewing
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
๐ Performance & Scalability | ๐ก Minor | โก Quick win
๐งฉ Analysis chain
๐ Script executed:
Repository: ContextualWisdomLab/aFIPC
Length of output: 3347
๐ Web query:
R data.frame subset assignment copy-on-modify complexity df$column[index] <- value docs๐ก Result:
In R, assignment operations like df$column[index] <- value are governed by copy-on-modify semantics, a mechanism designed to maintain an illusion of call-by-value while optimizing memory usage [1][2][3]. Key Concepts: - Copy-on-Modify: R objects are effectively immutable [1]. When you perform an assignment, R checks the reference count of the object (often stored in the 'named' field of its internal SEXP structure) [2][4][3]. If the reference count is greater than 1 (meaning other variables point to the same data), R duplicates the object before modifying it to ensure the original remains unchanged [1][4][3]. If the reference count is 1, R may be able to modify the object in place [4][3]. - Data Frame Structure: Data frames are lists of vectors [1]. Modifying a single column via df$column[index] <- value generally requires copying only that specific column vector [1]. However, modifying an entire row (e.g., df[index, ] <- value) requires copying every column in the data frame because the structure of the entire object is effectively being altered [1]. - Performance Complexity: Because R often performs these operations via high-level internal functions (like [<-.data.frame), multiple intermediate copies can occur depending on the specific operation, the number of references to the object, and internal function overhead [1]. Empirical testing using tools like tracemem is the most reliable way to determine if a copy is occurring in a specific context [1]. - Official Documentation: The behavior is rooted in the R internal memory management system (see the 'R Internals' manual) [3][5] and the S3 replacement methods for data frames [6]. For performance-critical code, it is recommended to avoid patterns that trigger excessive copying (such as growing data frames inside loops) and to monitor memory allocation empirically using tools provided in packages like pryr or base functions like tracemem [1][7][8].
Citations:
O(1)ํํ์ ์ํํ์ธ์.df$column[index] <- value๋[<-.data.frame์ค๋ฒํค๋๋ฅผ ์ค์ผ ์ ์์ง๋ง, R์ copy-on-modify์ ์ธ๋ฑ์ฑ/๋ณต์ฌ ๋น์ฉ ๋๋ฌธ์ ์์์ ํ ๋น์ O(1)์ด๋ผ๊ณ ๋จ์ ํ ์๋ ์์ต๋๋ค. โ์ค๋ฒํค๋๋ฅผ ์ค์ผ ์ ์๋คโ ์ ๋๋ก ๋ฐ๊ฟ ์ฃผ์ธ์.๐ค Prompt for AI Agents
Uh oh!
There was an error while loading. Please reload this page.