Skip to content

Confusion regarding environments invoked by "source" command

2 messages · Dennis Fisher, Duncan Murdoch

Dennis Fisher
# 
Colleagues,

R version 2.8.1 in OS X

Within a function (which is already within a function), I am sourcing  
a file.  The syntax of the command is something like (this is just an  
example; the actual code is much more complicated):
BIGFUNCTION	<- function()
	{
	DATAFRAME	<- [some commands to create a dataframe]
	MYFUNCTION(DATAFRAME)
	}
MYFUNCTION	<- function(DATAFRAME)
	{
	print(ls())
	exists("DATAFRAME")
	source("myfile", local=T)
	}

The file "myfile" contains the following:
	print(DATAFRAME)

When I execute BIGFUNCTION from the command line, R reports:
	Error in print(DATAFRAME) : object "DATAFRAME" not found
	Calls: BIGFUNCTION ... source -> eval.with.vis -> eval.with.vis ->  
print -> head
	Execution halted
However, the "print(ls())" command has just listed the existence of  
DATAFRAME and "exists(DATAFRAME) return TRUE
So, I am at a loss as to why ls() and "exists" see the object but  
print(DATAFRAME) command does not.

I tried "local=F" in the source command to no avail.
I also replaced "print(DATAFRAME)" with "print(str(DATAFRAME))" with  
the same outcome.
I assume that this is an error as to how I am managing environments  
but I cannot figure out a solution.  Any help would be appreciated.

Dennis



Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-415-564-2220
www.PLessThan.com
Duncan Murdoch
#
On 23/03/2009 6:06 PM, Dennis Fisher wrote:
This code works just as expected, once you make it syntactically 
correct.  I suspect you have something else wrong in the real case. 
Here's my log:

 > BIGFUNCTION<- function()
+ {
+ DATAFRAME<- data.frame(a=1:3,b=4:6)
+ MYFUNCTION(DATAFRAME)
+ }
 >
 > MYFUNCTION<- function(DATAFRAME)
+ {
+ print(ls())
+ exists("DATAFRAME")
+ source("myfile.R", local=T)
+ }
 > BIGFUNCTION()
[1] "DATAFRAME"
   a b
1 1 4
2 2 5
3 3 6

Duncan Murdoch