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Function and Environments

Explore the inner workings of functions in R and C, understanding the differences in how arguments are passed and variable scope is handled. Delve into local and global environments, and learn how values are shared and accessed.

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Function and Environments

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  1. Function and Environments What’s going on inside a function

  2. functions • In R, functions are called by value, that is, the value of the argument is copied into the function • In Fortran and C, functions are called by name, that is, only pointers to the argument variables are passed to the function • R avoids some weird function behavior, but it is wasteful in terms of space

  3. Local and Global • The value of any argument variable is local to the function, as is the result of any assignment to a variable inside the function • If R cannot find a variable locally (it is global), it will look outside the function for the value • The function’s arguments and local variables form an environment, nested within environments global to it, all the way to the top-level Global Environment

  4. Environments Global Environment d f1 → f2 → f1’s environment x (argument) v (local assignment) f2’s environment x (argument) v, d (local assignment)

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