Trying to understand environments is not for the faint of heart. If lists do what you want then I would stick with a list and not worry about the environments. Most of the time that you deal with environments everything happens automatically behind the scenes and you don't need to worry about the details.
If you want to learn more about environments there here is a start. Many of the ways of working with environments is the same as working with lists (you can access and assign with `[[` etc.) and there are `as.` functions to convert between them. The biggest difference is that environments use references instead of copies (powerful but dangerous). If you do something like mylist2 <- mylist mylist2$x <- 1 then mylist 2 will be a copy of mylist 1 and the value of x within mylist2 will be created or modified (but mylist will remain unchanged). However if you do the same thing with an environment then a copy is not made and the `x` variable in the original environment will be created or changed. This can be a big benefit when you have a large data object that needs to be passed to multiple functions, with an environment the data will never be copied, with a list or other object you may end up with multiple copies (though R is really good at not making copies when it does not need to, but sometimes you still end up with more copies than needed when R cannot tell if a copy is needed or not), but this is dangerous in that if you make any changes then the original is changed as well (the regular mechanism of making copies on changes protects the original). Environments also use hashing for name look ups which can speed things up when you have a large number of variables that you are accessing by name (but most usual cases are quick enough that you will not notice when using lists or other objects). Hope that helps, On Thu, Dec 19, 2013 at 10:17 AM, Julio Sergio Santana <julioser...@gmail.com> wrote: > Greg Snow <538280 <at> gmail.com> writes: > >> >> The take home message that you should be learning from your struggles >> is to "Not Use The 'assign' Function!" and "Do Not Use Global >> Variables Like This". >> >> R has lists (and environments) that make working with objects that are >> associated with each other much simpler and fits better with the >> functional programming style of R. >> > > Thanks, Greg! > > Yours is a very smart solution to the problem I posed. > > By the way, what I'm trying to do is reading from a file a set of user given > parameters, in two paired columns: parameter-name, value; and then, managing > these parameters inside my R program. Now I do understand a bit more about > lists. What about environments? Are they similar to lists, and when, and how > are they created? > > Best regrards, > > -Sergio. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Gregory (Greg) L. Snow Ph.D. 538...@gmail.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
