R help - Sep 2007 - testing the contents of an environment

Suppose I want to delete everything in my working directory that is not 
a function. It seems that

sapply(ls(),is.function)

always returns FALSE, because ls() returns objects of mode character. 
How do I evaluate is.function(), not on a character string, but on the 
object that character string represents?

Thanks,

Tim

Need to use 'get':
> ls(9)
 [1] "c.Factor"          "cls.console"      
"date2POSIX"
"Default.par"       "delete.NULLs"
 [6] "f.apdex"           "f.area"           
"f.axis"
"f.HHMMSS2hr"       "f.hr2HHMMSS"
[11] "f.integrate"       "f.queue"          
"f.TimeAxis"
"file.size"         "function.print"
[16] "generate.stats"    "HrsInDay"         
"level.plot"
"list.subset"       "ls.obj"
[21] "my.axis.POSIXct"   "my.func"          
"my.ls"
"my.stats"          "plot.sar"
[26] "plot.srx.file"     "plotReset"        
"poly.graph"
"poly.graph.legend" "poly.graph1"
[31] "print.wide"        "r.time.cvt"       
"read.sar"
"ReadVMstat"        "sar.levelplot"
[36] "setParms"          "Setwd"            
"time2POSIXct"
"unix2EXCEL"        "unix2POSIXct"
[41] "x.createColors"
> sapply(ls(9), function(x) is.function(get(x)))
         c.Factor       cls.console        date2POSIX
Default.par      delete.NULLs
             TRUE              TRUE              TRUE
FALSE              TRUE
          f.apdex            f.area            f.axis
f.HHMMSS2hr       f.hr2HHMMSS
             TRUE              TRUE              TRUE
TRUE              TRUE
      f.integrate           f.queue        f.TimeAxis
file.size    function.print
             TRUE              TRUE              TRUE
TRUE              TRUE
   generate.stats          HrsInDay        level.plot
list.subset            ls.obj
             TRUE              TRUE              TRUE
TRUE              TRUE
  my.axis.POSIXct           my.func             my.ls
my.stats          plot.sar
             TRUE              TRUE              TRUE
TRUE              TRUE
    plot.srx.file         plotReset        poly.graph
poly.graph.legend       poly.graph1
             TRUE              TRUE              TRUE
TRUE              TRUE
       print.wide        r.time.cvt          read.sar
ReadVMstat     sar.levelplot
             TRUE              TRUE              TRUE
TRUE              TRUE
         setParms             Setwd      time2POSIXct
unix2EXCEL      unix2POSIXct
             TRUE              TRUE              TRUE
TRUE              TRUE
   x.createColors
             TRUE
>

On 9/27/07, Tim Bergsma <timb at metrumrg.com>
wrote:
> Suppose I want to delete everything in my working directory that is not
> a function. It seems that
>
> sapply(ls(),is.function)
>
> always returns FALSE, because ls() returns objects of mode character.
> How do I evaluate is.function(), not on a character string, but on the
> object that character string represents?
>
> Thanks,
>
> Tim
>
> ______________________________________________
> 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.
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

On 28/09/2007, at 6:52 AM, Tim Bergsma wrote:
> Suppose I want to delete everything in my working directory that is  
> not
> a function. It seems that
>
> sapply(ls(),is.function)
>
> always returns FALSE, because ls() returns objects of mode character.
> How do I evaluate is.function(), not on a character string, but on the
> object that character string represents?
sapply(ls(),function(x){is.function(get(x))})

One must distinguish between an object and its name.

(See ``Alice Through the Looking-Glass'' by Lewis Carroll aka Rev.  
Charles L. Dodgson. :-) )

			cheers,

				Rolf Turner

######################################################################
Attention:\ This e-mail message is privileged and confidenti...{{dropped}}

On 9/27/07, Rolf Turner <r.turner at auckland.ac.nz>
wrote:
>
> On 28/09/2007, at 6:52 AM, Tim Bergsma wrote:
>
> > Suppose I want to delete everything in my working directory that is
> > not
> > a function. It seems that
> >
> > sapply(ls(),is.function)
> >
> > always returns FALSE, because ls() returns objects of mode character.
> > How do I evaluate is.function(), not on a character string, but on the
> > object that character string represents?
>
> sapply(ls(),function(x){is.function(get(x))})
A conceptually simpler alternative is

sapply(ls(), exists, mode = "function", inherits = FALSE)

-Deepayan