R help - Jun 2009 - How to parse and eval a collection of items

Let's say I have, for some reason, a bunch of scalars (i.e. 
single-valued variables) and I want to merge them all into a single 
vector of values.  Can someone recommend a better function, or simpler 
way, to do so than the following?

Suppose my scalars' names are foo1, foo2, foo3, foo1high, foo2high, 
foo3lo2, etc.  Then I can do:



 >ls(pat='foo')->thels


 >mapply(function(x) eval(as.name(thels[x])),seq(1:length(thels)))->vecfoo


I was hoping for some way to avoid creating a function and an *apply 
call.  Conceptually, eval(as.name(c(thels)))  which of course doesn't work.

thanks
Carl

You can get the values using get:

sapply(ls(patt = "foo"), get)


On Thu, Jun 18, 2009 at 6:25 PM, Carl Witthoft <carl@witthoft.com> wrote:
> Let's say I have, for some reason, a bunch of scalars (i.e.
single-valued
> variables) and I want to merge them all into a single vector of values. 
Can
> someone recommend a better function, or simpler way, to do so than the
> following?
>
> Suppose my scalars' names are foo1, foo2, foo3, foo1high, foo2high,
> foo3lo2, etc.  Then I can do:
>
>
>
> >ls(pat='foo')->thels
>
>
> >mapply(function(x)
eval(as.name(thels[x])),seq(1:length(thels)))->vecfoo
>
>
> I was hoping for some way to avoid creating a function and an *apply call.
>  Conceptually, eval(as.name(c(thels)))  which of course doesn't work.
>
> thanks
> Carl
>
> ______________________________________________
> 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]

On 19/06/2009, at 9:25 AM, Carl Witthoft wrote:
> Let's say I have, for some reason, a bunch of scalars (i.e.
> single-valued variables) and I want to merge them all into a single
> vector of values.  Can someone recommend a better function, or simpler
> way, to do so than the following?
>
> Suppose my scalars' names are foo1, foo2, foo3, foo1high, foo2high,
> foo3lo2, etc.  Then I can do:
>
>
>
>> ls(pat='foo')->thels
>
>
>> mapply(function(x) eval(as.name(thels[x])),seq(1:length(thels)))- 
>> >vecfoo
>
>
> I was hoping for some way to avoid creating a function and an *apply
> call.  Conceptually, eval(as.name(c(thels)))  which of course  
> doesn't work.
Does

	do.call(c,thels)

work?

	cheers,

		Rolf Turner

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This does not use an apply:

unlist(mget(thels, .GlobalEnv))


On Thu, Jun 18, 2009 at 5:25 PM, Carl Witthoft<carl at witthoft.com>
wrote:
> Let's say I have, for some reason, a bunch of scalars (i.e.
single-valued
> variables) and I want to merge them all into a single vector of values.
?Can
> someone recommend a better function, or simpler way, to do so than the
> following?
>
> Suppose my scalars' names are foo1, foo2, foo3, foo1high, foo2high,
foo3lo2,
> etc. ?Then I can do:
>
>
>
>>ls(pat='foo')->thels
>
>
>>mapply(function(x)
eval(as.name(thels[x])),seq(1:length(thels)))->vecfoo
>
>
> I was hoping for some way to avoid creating a function and an *apply call.
> ?Conceptually, eval(as.name(c(thels))) ?which of course doesn't work.
>
> thanks
> Carl
>
> ______________________________________________
> 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.
>