![]() ![]() Knowing this is rarely practical but it can be used for some fun shenanigans. ‘ (left-to-right assignment), though syntactically distinct, always call the same function. What are the differences between the assignment operators = and ->’ rightwards assignment This is because = is lower precedence than <-, as shown on the ?Syntax help page. We might expect that x <- y = 5 would then be `<-`(x, `=`(y, 5))īut actually it gets interpreted as `=`(`<-`(x, y), 5) Secondly, it's clearer if we use prefix notation for assignment. ![]() You can see that more clearly by explicitly printing, for example print(x <- 2 + 3). To understand what is happening, you need to know that assignment silently returns the value that was assigned. The parser chooses to resolve the bits of the expression in different orders depending on whether = or <- was used. ![]() R's syntax contains many ambiguous cases that have to be resolved one way or another. The answer to the question "Why does x <- y = 5 throw an error but not x <- y <- 5?" is "It's down to the magic contained in the parser". Tidy_source(text = "x=1:5", arrow = TRUE) If you prefer writing = to <- but want to use the more common assignment symbol for publicly released code (on CRAN, for example), then you can use one of the tidy_* functions in the formatR package to automatically replace = with <. Ctrl + = in Architect, Alt + - in RStudio ( Option + - under macOS), Shift + - (underscore) in emacs+ESS. This is very helpful for a few reasons: it allows you to have more compute resources closer to your data, it provides a uniform environment for teams that makes it easier to collaborate, and it provides controls for administrators to monitor and scale work. Most R IDEs have keyboard shortcuts to make <- easier to type. RStudio Server Pro - Very similar to the Desktop IDE, but runs on a server. Note that the spaces help to clarify situations like x<-3 There is a general preference among the R community for using <- for assignment (other than in function signatures) for compatibility with (very) old versions of S-Plus. In this case, x is declared in the user workspace, so you can use it after the function call has been completed. In this case, x is declared within the scope of the function, so it does not exist in the user workspace. The difference in assignment operators is clearer when you use them to set an argument value in a function call. ![]()
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