R help - Oct 2011 - How to write a list object's name to a new dataframe in that list object

Hello R-helpers,

I have a list that only contains dataframes. Each element of the list
(i.e., each dataframe) has a unique name ("one" through
"ten"). I wish
to add a new column (called "NAME") to each list element (i.e each
datarame) and I want that column to contain the name of it's list
element.

e.g. the list element (i.e., dataframe) called "one" would get a new
column called "NAME" that would contain the word "one" in
every row.

Could anyone help with that?

Many thanks,

Mark Na

It's inefficient but try this:

Suppose your list is L:

mapply(function(x,y) cbind(x, data.frame(NAME=rep(y,NROW(x)))), L, names(L),
simplify = F)

Code is untested however - let me know if this doesn't work and I'll get
to a computer and clean it up.

Michael Weylandt


On Oct 7, 2011, at 11:17 PM, Mark Na <mtb954 at gmail.com> wrote:
> Hello R-helpers,
> 
> I have a list that only contains dataframes. Each element of the list
> (i.e., each dataframe) has a unique name ("one" through
"ten"). I wish
> to add a new column (called "NAME") to each list element (i.e
each
> datarame) and I want that column to contain the name of it's list
> element.
> 
> e.g. the list element (i.e., dataframe) called "one" would get a
new
> column called "NAME" that would contain the word "one"
in every row.
> 
> Could anyone help with that?
> 
> Many thanks,
> 
> Mark Na
> 
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