Question about assigning & scope

[Jordão, Felipe <Felipe.Jordao@moodys.com>]

Hi all,

 

I’m having a bit of difficulty understanding this scope business. I’ve tried going through the help and googling to no avail. It is probably very simple for you S veterans out there.

 

What I would like to do is modify a column in a global data frame from within a function. For example, the current code I have looks like this and works as I want it to:

 

my.dataframe <- data.frame(state.x77, row.names=state.abb)

my.dataframe$Income <- new.values.from.some.calculation

 

I want to change it so it’s like this:

 

my.function <- function() {

       my.dataframe$Income <- new.values.from.some.calculation

}

 

When I call my.function, I get a message saying that I need to assign my.dataframe locally before replacement. I tried using code like this

 

my.function <- function() {

       assign("my.dataframe[,\"Income\"]", new.values.from.some.calculation)

}

 

but it also didn’t work. I don’t get an error message, but the Income column is not changed. The data I’m working with is big, so it’s not efficient to pass it into the function, change it, then return it.

 

thanks,
Felipe

 

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