R help - Feb 2011 - Populate a list / recursively set list values to NA

Hello all,

Maybe I'm being thick, but I was trying to figure out a simple way to create
a list with the same dimension of another list, but populated with NA
values.

    masterlist = list(
            aa=list(
                    a=matrix(rnorm(100),10,10),
                    b=matrix(rnorm(130),13,10),
                    c=matrix(rnorm(140),14,10)),
            bb=list(
                    a=matrix(rnorm(100),10,10),
                    b=matrix(rnorm(110),11,10),
                    c=matrix(rnorm(120),12,10)),
            cc=list(
                    a=matrix(rnorm(100),10,10),
                    b=matrix(rnorm(100),10,10),
                    c=matrix(rnorm(100),10,10)),
            dd=matrix(rnorm(225),15,15))
    str(masterlist)
    ## Yay!  A new list that's just like the master list!
    newlist = masterlist
    ## BOO!  Can't just set all the values to NA!
    newlist = masterlist * NA

    ## This works... but requires knowledge of the structure
    newlist = masterlist
    newlist[['aa']] = lapply(masterlist[['aa']], function(x) x *
NA)
    newlist[['bb']] = lapply(masterlist[['bb']], function(x) x *
NA)
    newlist[['cc']] = lapply(masterlist[['cc']], function(x) x *
NA)
    newlist[['dd']] = masterlist[['dd']] * NA
    str(newlist)

At this point I thought a recursive function would be a good idea, but I
wasn't sure how to keep the nice list names.

I feel sure that this must be something that others have already done.

Thank you!!!

PS:
I found an email in the archive about it, but that email un-helpfully
instructed the user to LEARN HOW TO USE EMAIL.  Not sure how to use email to
initialize a list. so if someone could explain to me how to use emails to
initialize / populate a list, that would be cool also.
Also, I did type ?list and ?lapply, and I did read the help files.  In fact,
I learned about the very helpful vector("list", length) command
yesterday!
Pretty cool!
I'm not opposed to looking at the help, but please provide some hint about
what direction to take with the help.  Even a small hint will do!!

If you want to yell at me about reading the help or whatever, that's fine.
But please do so offline so that the archives will be more valuable for
future users.

	[[alternative HTML version deleted]]

Gene,

?rapply is a recursive version of ?lapply, and should work.

rapply(masterlist, function(x) x*NA, how = "replace")


--Erik

Gene Leynes wrote:
> Hello all,
> 
> Maybe I'm being thick, but I was trying to figure out a simple way to
create
> a list with the same dimension of another list, but populated with NA
> values.
> 
>     masterlist = list(
>             aa=list(
>                     a=matrix(rnorm(100),10,10),
>                     b=matrix(rnorm(130),13,10),
>                     c=matrix(rnorm(140),14,10)),
>             bb=list(
>                     a=matrix(rnorm(100),10,10),
>                     b=matrix(rnorm(110),11,10),
>                     c=matrix(rnorm(120),12,10)),
>             cc=list(
>                     a=matrix(rnorm(100),10,10),
>                     b=matrix(rnorm(100),10,10),
>                     c=matrix(rnorm(100),10,10)),
>             dd=matrix(rnorm(225),15,15))
>     str(masterlist)
>     ## Yay!  A new list that's just like the master list!
>     newlist = masterlist
>     ## BOO!  Can't just set all the values to NA!
>     newlist = masterlist * NA
> 
>     ## This works... but requires knowledge of the structure
>     newlist = masterlist
>     newlist[['aa']] = lapply(masterlist[['aa']],
function(x) x * NA)
>     newlist[['bb']] = lapply(masterlist[['bb']],
function(x) x * NA)
>     newlist[['cc']] = lapply(masterlist[['cc']],
function(x) x * NA)
>     newlist[['dd']] = masterlist[['dd']] * NA
>     str(newlist)
> 
> At this point I thought a recursive function would be a good idea, but I
> wasn't sure how to keep the nice list names.
> 
> I feel sure that this must be something that others have already done.
> 
> Thank you!!!
> 
> PS:
> I found an email in the archive about it, but that email un-helpfully
> instructed the user to LEARN HOW TO USE EMAIL.  Not sure how to use email
to
> initialize a list. so if someone could explain to me how to use emails to
> initialize / populate a list, that would be cool also.
> Also, I did type ?list and ?lapply, and I did read the help files.  In
fact,
> I learned about the very helpful vector("list", length) command
yesterday!
> Pretty cool!
> I'm not opposed to looking at the help, but please provide some hint
about
> what direction to take with the help.  Even a small hint will do!!
> 
> If you want to yell at me about reading the help or whatever, that's
fine.
> But please do so offline so that the archives will be more valuable for
> future users.
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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