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Ivan Calandra

2010-May-19 14:56 UTC

[R] save in for loop

Dear users,

My problem concerns save() within a for loop.
Here is my code:

for (i in 1:4) {
  temp <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
  filename <- paste("file", i, sep="")
  assign(filename, temp)
  save(filename, file=paste(filename, ".rda", sep=""))
}

As you can see, save() doesn't work as I would like: (1) the object 
saved is called "filename" (instead of "file1",
"file2", etc), and (2)
it of course contains only the name (as character) instead of the data.frame

How can I fix it?

I usually use lists for such cases, but (1) in the real thing, it gets 
complicated with the names and structure (because I want to save lists 
with 3 dimensions instead of simple data.frames, as in this example) and 
(2) I prefer saving each list separately (and I cannot save only one 
element of an object either).

I'm not sure I'm really clear because it's difficult for me to
explain
it, but I hope you'll understand (and let me know what you would help 
you to understand)

Thank you in advance
Ivan

-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. S?ugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra at uni-hamburg.de

**********
http://www.for771.uni-bonn.de
http://webapp5.rrz.uni-hamburg.de/mammals/eng/mitarbeiter.php

Shi, Tao

2010-May-19 18:05 UTC

head link

[R] save in for loop

Ivan,

Try this:

eval(parse(text=paste("save(file", i, ", file=\"file",
i, ".RData\")", sep="")))

...Tao




----- Original Message ----> From: Ivan Calandra <ivan.calandra at uni-hamburg.de>
> To: r-help at r-project.org
> Sent: Wed, May 19, 2010 7:56:44 AM
> Subject: [R] save in for loop
> 
> Dear users,
My problem concerns save() within a for loop.
Here is my > code:
for (i in 1:4) {
temp <- data.frame(a=(i+1):(i+10), > b=LETTERS[(i+1):(i+10)])filename <- paste("file", i, sep="")
> assign(filename, temp)
save(filename, file=paste(filename, ".rda", > sep=""))}

As you can see, save() doesn't work as I would like: (1)
> the object saved is called "filename" (instead of
"file1", "file2", etc), and
> (2) it of course contains only the name (as character) instead of the 
> data.frame
How can I fix it?

I usually use lists for such cases, > but (1) in the real thing, it gets complicated with the names and structure
> (because I want to save lists with 3 dimensions instead of simple
data.frames,
> as in this example) and (2) I prefer saving each list separately (and I
cannot
> save only one element of an object either).
I'm not sure I'm really clear > because it's difficult for me to explain it, but I hope you'll
understand (and
> let me know what you would help you to understand)
Thank you in > advanceIvan

-- Ivan CALANDRA
PhD Student
University of > HamburgBiozentrum Grindel und Zoologisches Museum
Abt. > S?ugetiereMartin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 > 42838 6231
> href="mailto:ivan.calandra at uni-hamburg.de">ivan.calandra at
uni-hamburg.de
**********
http://www.for771.uni-bonn.de
http://webapp5.rrz.uni-hamburg.de/mammals/eng/mitarbeiter.php

______________________________________________
> ymailto="mailto:R-help at r-project.org" 
> href="mailto:R-help at r-project.org">R-help at r-project.org
mailing list
> href="https://stat.ethz.ch/mailman/listinfo/r-help" target=_blank
> >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.

Jorge Ivan Velez

2010-May-19 18:29 UTC

head link

[R] save in for loop

Hi Ivan,

How about this?

i <- 1:4
sapply(i,
function(i){
x <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
 save(x, file = paste("file", i, ".rda", sep=""))
}
 )

HTH,
Jorge


On Wed, May 19, 2010 at 10:56 AM, Ivan Calandra <> wrote:
> Dear users,
>
> My problem concerns save() within a for loop.
> Here is my code:
>
> for (i in 1:4) {
>  temp <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
>  filename <- paste("file", i, sep="")
>  assign(filename, temp)
>  save(filename, file=paste(filename, ".rda", sep=""))
> }
>
> As you can see, save() doesn't work as I would like: (1) the object
saved
> is called "filename" (instead of "file1",
"file2", etc), and (2) it of
> course contains only the name (as character) instead of the data.frame
>
> How can I fix it?
>
> I usually use lists for such cases, but (1) in the real thing, it gets
> complicated with the names and structure (because I want to save lists with
> 3 dimensions instead of simple data.frames, as in this example) and (2) I
> prefer saving each list separately (and I cannot save only one element of
an
> object either).
>
> I'm not sure I'm really clear because it's difficult for me to
explain it,
> but I hope you'll understand (and let me know what you would help you
to
> understand)
>
> Thank you in advance
> Ivan
>
> --
> Ivan CALANDRA
> PhD Student
> University of Hamburg
> Biozentrum Grindel und Zoologisches Museum
> Abt. Säugetiere
> Martin-Luther-King-Platz 3
> D-20146 Hamburg, GERMANY
> +49(0)40 42838 6231
> ivan.calandra@uni-hamburg.de
>
> **********
> http://www.for771.uni-bonn.de
> http://webapp5.rrz.uni-hamburg.de/mammals/eng/mitarbeiter.php
>
> ______________________________________________
> 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.
>
	[[alternative HTML version deleted]]

Ivan Calandra

2010-May-20 08:30 UTC

head link

[R] save in for loop

Hi Dennis,

What is the problem with using eval(parse(text=...))? Is there a reason 
why not to use it?
Of course, in that case, "list" within save() is much easier and works
perfectly.

In any case, thanks for your explanations :)
Ivan

Le 5/20/2010 10:26, Dennis Murphy a écrit :> Hi:
>
> On Thu, May 20, 2010 at 12:43 AM, Ivan Calandra 
> <ivan.calandra@uni-hamburg.de
<mailto:ivan.calandra@uni-hamburg.de>>
> wrote:
>
>     Thanks to all of you for your answers!
>
>     Peter's is definitely the easiest :)
>     for (i in 1:4) {
>       temp <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
>       filename <- paste("file", i, sep="")
>       assign(filename, temp)
>       save(list=c(filename), file=paste(filename, ".rda",
sep=""))
>     }
>
>
>
> Tao, I don't understand why you have backslashes before
"file" and after
>
>     .rda. I guess it's something about regular expression, but I'm
still
>     very new to it.
>     eval(parse(text=paste("save(file", i, ",
file=\"file", i, ".rda\")",
>     sep="")))
>
>
> eval(parse(text = ...)) is necessary sometimes, but usually not. This 
> is one of
> the 'not' cases. Re your question, the backslash is used to escape
the
> quote
> within the quote so that it is rendered properly when parsed/evaluated.
>
>
>     Jorge, your solution does not work... I've just copy/pasted your
code.
>     My second great weakness is with the apply() family. So maybe I
>     have to
>     adjust some part of the code to my needs, but I'm unable to do it.
>     i <- 1:4
>     sapply(i, function(i) {
>       x <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
>     save(x, file = paste("file", i, ".rda",
sep=""))
>     } )
>
>
> I tried a variation on this solution, and discovered that whenever you 
> load
> a .rda file, the name of the object is the same in all of them. It 
> 'works' in the
> sense that the right object is saved to each of the file*.rda; 
> however, when
> loaded, all the objects have the same name x, so in the end it doesn't 
> really
> work.
>
> Peter figured out that saving the object as a list was the key - that 
> way,
> the name of the object saved is the value of filename (file*) so that 
> when it
> is loaded back in, the object names are distinct.
>
> A more interesting question than it appeared at first...
>
> Dennis
>
>
>     Anyway, everything's now fine!
>     Thanks again.
>     Ivan
>
>
>     Le 5/19/2010 20:29, Jorge Ivan Velez a écrit :
>     > Hi Ivan,
>     >
>     > How about this?
>     >
>     > i <- 1:4
>     > sapply(i,
>     > function(i){
>     > x <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
>     > save(x, file = paste("file", i, ".rda",
sep=""))
>     > }
>     > )
>     >
>     > HTH,
>     > Jorge
>
>     Le 5/19/2010 22:20, Peter Ehlers a écrit :
>     > On 2010-05-19 12:05, Shi, Tao wrote:
>     >> Ivan,
>     >>
>     >> Try this:
>     >>
>     >> eval(parse(text=paste("save(file", i, ",
file=\"file", i,
>     >> ".RData\")", sep="")))
>     >>
>     >> ...Tao
>     >>
>     >
>     > Or just use 'list=' like this:
>     >
>     > for (i in 1:4) {
>     >   temp <- data.frame(a=(i+1):(i+10), b=LETTERS[(i+1):(i+10)])
>     >   filename <- paste("file", i, sep="")
>     >   assign(filename, temp)
>     >   save(list=c(filename), file=paste(filename, ".rda",
sep=""))
>     > }
>     >
>     >  -Peter Ehlers
>     >
>     >>
>     >>
>     >> ----- Original Message ----
>     >>> From: Ivan Calandra<ivan.calandra@uni-hamburg.de
>     <mailto:ivan.calandra@uni-hamburg.de>>
>     >>> To: r-help@r-project.org
<mailto:r-help@r-project.org>
>     >>> Sent: Wed, May 19, 2010 7:56:44 AM
>     >>> Subject: [R] save in for loop
>     >>>
>     >>> Dear users,
>     >>
>     >> My problem concerns save() within a for loop.
>     >> Here is my
>     >>> code:
>     >>
>     >> for (i in 1:4) {
>     >> temp<- data.frame(a=(i+1):(i+10),
>     >>> b=LETTERS[(i+1):(i+10)])
>     >> filename<- paste("file", i, sep="")
>     >>
>     >>> assign(filename, temp)
>     >> save(filename, file=paste(filename, ".rda",
>     >>> sep=""))
>     >> }
>     >>
>     >> As you can see, save() doesn't work as I would like: (1)
>     >>> the object saved is called "filename" (instead
of "file1",
>     "file2",
>     >>> etc), and
>     >>> (2) it of course contains only the name (as character)
instead
>     of the
>     >>> data.frame
>     >>
>     >> How can I fix it?
>     >>
>     > [snip]
>     >
>
>     --
>     Ivan CALANDRA
>     PhD Student
>     University of Hamburg
>     Biozentrum Grindel und Zoologisches Museum
>     Abt. Säugetiere
>     Martin-Luther-King-Platz 3
>     D-20146 Hamburg, GERMANY
>     +49(0)40 42838 6231
>     ivan.calandra@uni-hamburg.de
<mailto:ivan.calandra@uni-hamburg.de>
>
>     **********
>     http://www.for771.uni-bonn.de
>     http://webapp5.rrz.uni-hamburg.de/mammals/eng/mitarbeiter.php
>
>
>            [[alternative HTML version deleted]]
>
>
>     ______________________________________________
>     R-help@r-project.org <mailto: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.
>
>
-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra@uni-hamburg.de

**********
http://www.for771.uni-bonn.de
http://webapp5.rrz.uni-hamburg.de/mammals/eng/mitarbeiter.php


	[[alternative HTML version deleted]]

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