R help - Jun 2013 - Loading an .RData file and assigning the loaded objects within a loop

Hi all,

I tried to look this up online, but am still feeling a little stuck.

I have a bunch of Rdata files in side my directory, and I would like to
load all of them in a loop. Each time the next is read in, it would
over-write the previously read in object because they will be assigned the
same workspace object name.

Is there anyway for each individually read in Rdata object to be assigned a
new name?

Thanks!
JEremy

	[[alternative HTML version deleted]]

use 'lapply' to read in the .RData file.  Therefore each file is stored
as an element of a list thatb
 you can access and change as necessary.

Sent from my iPad

On Jun 1, 2013, at 6:18, Jeremy Ng <jeremy.ng.wk1990 at gmail.com> wrote:
> Hi all,
> 
> I tried to look this up online, but am still feeling a little stuck.
> 
> I have a bunch of Rdata files in side my directory, and I would like to
> load all of them in a loop. Each time the next is read in, it would
> over-write the previously read in object because they will be assigned the
> same workspace object name.
> 
> Is there anyway for each individually read in Rdata object to be assigned a
> new name?
> 
> Thanks!
> JEremy
> 
>    [[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at 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.

Within lapply load the file and return the value of the thing or
things in the file you want. Something like this:

 > files
[1] "x1.RData" "x2.RData" "x3.RData"
"x4.RData"

 > lapply(files,function(z){load(z);x})
[[1]]
[1] 1

[[2]]
[1] 22

[[3]]
[1] 333

[[4]]
[1] 4444

Each of my files contains a single number stored in an object called
'x'. Within the loop 'x' has the value just loaded from the
file.

Another method is to use the environment argument of load to save into
an environment other than the global one...




On Sat, Jun 1, 2013 at 11:52 AM, Jim Holtman <jholtman at gmail.com>
wrote:
> use 'lapply' to read in the .RData file.  Therefore each file is
stored as an element of a list thatb
>  you can access and change as necessary.
>
> Sent from my iPad
>
> On Jun 1, 2013, at 6:18, Jeremy Ng <jeremy.ng.wk1990 at gmail.com>
wrote:
>
>> Hi all,
>>
>> I tried to look this up online, but am still feeling a little stuck.
>>
>> I have a bunch of Rdata files in side my directory, and I would like to
>> load all of them in a loop. Each time the next is read in, it would
>> over-write the previously read in object because they will be assigned
the
>> same workspace object name.
>>
>> Is there anyway for each individually read in Rdata object to be
assigned a
>> new name?
>>
>> Thanks!
>> JEremy
>>
>>    [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at 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.
>
> ______________________________________________
> R-help at 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.

On Sat, Jun 1, 2013 at 6:18 AM, Jeremy Ng <jeremy.ng.wk1990 at gmail.com>
wrote:
> Hi all,
>
> I tried to look this up online, but am still feeling a little stuck.
>
> I have a bunch of Rdata files in side my directory, and I would like to
> load all of them in a loop. Each time the next is read in, it would
> over-write the previously read in object because they will be assigned the
> same workspace object name.
>
> Is there anyway for each individually read in Rdata object to be assigned a
> new name?
>
If Files is a character vector containing the filenames then this
creates a list witih one componet per RData file. The list names will
be the file names.  Each component is itself a list containing the
objects in that file:

    L <- sapply(Files, function(x) mget(load(x)), simplify = FALSE)

(If it is known that each RData file contains only a single object
then mget could be replaced with get in which case each component of L
would be the object in the respective file.  In that case you will
lose the object names but as you indicated they are all the same that
likely won' t matter.)

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