Environments in R

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** Things under legendu.net/outdated are outdated technologies that the author does not plan to update any more. Please look for better alternatives. **

1. The option pos=1 of the function assign refers to the global environment, i.e., the user’s workspace. Containers in R are 1-based, so it is easy to understand (and remember) that R use 1 to stand for the global enviroment (user’s workspace). Notice that ..GlobalEnv is a variable standing for the global environment and globalenv() returns the global environment, pos=1 is equivalent to say pos=.GlobalEnv or pos=globalenv(). If you want to create a global variable in a function, you can use the function assign by specifying pos=1 (or pos=.GlobalEnv or pos=globalenv). Another easier but less powerful way is to the <<- or ->> to assign/create global variables.

2. The function new.env creates a new environment. If you want to source in some code but would rather let the code in a new environment (so that the environment sourcing the code is not contaminated), you can use source(path_to_file, local=new.env()).

3. The function emptyenv returns an immutable empty environment. The empty environment is not used to evaluate expressions or run code but rather to check whether nested environments end.