From: Fernando Saldanha
I have noticed that after I ran a batch script multiple times I get
multiple copies of a package's name when I call search(). Is this a
problem?
[1] ".GlobalEnv" "DF" "DF"
[4] "DF" "DF" "DF"
multiple copies here ...
[13] "DF" "DF" "DF"
other packages here ...
[28] "package:quadprog" "package:car" "package:methods"
[31] "package:stats" "package:graphics" "package:grDevices"
[34] "package:utils" "package:datasets" "Autoloads"
[37] "package:base"
The following strange (to me) behavior that may be related. Suppose I
have a variable x that is in the global environment, and also there is
an 'x' in a dataframe called DF. Then I remove the variable x from the
Global Environment, with
remove('x', pos = 1)
At this point if I call remove again in the same way I get an error:
the variable x does not exist anymore. However, at this point I also
can check that DF$x exists. So far so good.
Further down in my code I have an assignment of the type
x[i] <- something (*)
which works fine, except that then if I look at x[i] and DF$x[i] they
are different. So it looks like x was recreated in the Global
Environment, which I actually can check by typing
.GlobalEnv$x.
On the other hand, if I put in my code something like
newvar[i] <- something
where newvar was never defined, then I get an error. I was hoping that
the statement (*)
above would assign to the variable DF$x. But it looks like (although
that is probably not the correct explanation) that the interpreter
somehow "remembers" that once there was a variable x in the global
environment and accepts the assignment to x[i], recreating that
variable.
Any insights on this?
Many thanks,
Fernando