I was trying to see if data.table could speed up a gsub pattern matching function over a list.. Data for reprex. Analyzing twitter data using R. GitHub Gist: instantly share code, notes, and snippets. I want to design a function that looks at "everything" contained din a list, and anytime it finds the text string "pattern" replace it with "x". The sub() function (short for substitute) in R searches for a pattern in text and replaces this pattern with replacement text.You use sub() to substitute text for text, and you use its cousin gsub() to substitute all occurrences of a pattern. Dates won't be affected. … Let me show you how this works. The solution with loop works perfectly fine for me, I'm just trying to learn more R and explore as many methods as possible. - [Instructor] With R, you can work with strings. Each data frame is 6500 rows, 2 columns, and generally representative of my actual data. Details gsubfn is an R package used for string matching, substitution and parsing. A seemingly small generalization of gsub, namely allow the replacement string to be a replacement function, list, formula or proto object, can result in signiﬁcantly increased power and applicability. It's a list of 3 data frames with some asterisks placed here and there. … First, I've created a vector called someText … that just contains two lines of … From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Dick Harray Sent: Friday, February 04, 2011 7:37 AM To: r-help at r-project.org Subject: [R] lapply, strsplit, and list elements Hi there, I have a problem about lapply, strsplit, and accessing list elements, which I don't understand or cannot solve: I had a question re:using "gsub" (or some similar functions) on the contents of a list. The POSIX 1003.2 mode of gsub and gregexpr does not work correctly with repeated word-boundaries (e.g., pattern = "\b").Use perl = TRUE for such matches (but that may not work as expected with non-ASCII inputs, as the meaning of ‘word’ is system-dependent).. sapply(x, f, simplify = FALSE, USE.NAMES = FALSE) is the same as lapply(x, f). By using "^_$" as our pattern in gsub, we're saying to look for exactly that pattern. This is an introductory post about using apply, sapply and lapply, best suited for people relatively new to R or unfamiliar with these functions. (The g in gsub() stands for global. There is a part 2 coming that will look at density plots with ggplot , but first I thought I would go on a tangent to give some examples of the apply family, as they come up a lot working with R. Warning. lapply returns a list of the same length as X, each element of which is the result of applying FUN to the corresponding element of X. sapply is a user-friendly version and wrapper of lapply by default returning a vector, matrix or, if simplify = "array", an array if appropriate, by applying simplify2array(). … And there are times when you'll want to replace one string … with another and for that we have sub and gsub. Tag: r,for-loop,gsub,sapply Trying to avoid using a for loop in the following code by utilizing sapply , if at all possible. By Andrie de Vries, Joris Meys . Generalized "’gsub’" and associated functions. Performance considerations. It seems like although rapply can handle keeping the data as a list, the data.frame attribute is lost (hence the extra lapply(..., as.data.frame). I also wish to preserve the "structure" of the original list. The resulting I am experimenting with some of the common r functions. https://www.datasciencemadesimple.com/sub-gsub-function-in-r The reason this doesn't work is gsub takes Regular Expressions for the pattern argument, and + is a metacharacter than means "repeat one or more times", so "banana + banana" is interpreted as 'banana' followed by one or more spaces, followed by a space, followed by 'banana'