[R] Getting data from an *.RData file into a data.frame object.

[Ivan Calandra]

I like using saveObject() and loadObject() from package R.utils because 
you can assign the data to a new object.

Like this:
library(R.utils)
saveObject(df, file="file.Rbin")
df2 <- loadObject("file.Rbin")

HTH,
Ivan

Le 8/12/2011 21:38, peter dalgaard a écrit :
> On Aug 12, 2011, at 21:12 , Ed Heaton wrote:
>
>> Hi, all.
>>
>> I'm new to R.  I've been a SAS programmer for 20 years.
>>
>> I seem to be having trouble with the most basic task - bringing a table in
>> an *.RData file into a data.frame object.
>>
>> Here's how I created the *.RData file.
>>
>> library(RODBC)
>> db<- odbcConnect("*******")
>> df<- sqlQuery(
>>     db
>>   , "select * from schema.table where year(someDate)=2006"
>> )
>> save(
>>     df
>>   , file="C:/Documents and Settings/userName/My Documents/table2006.RData"
>> )
>> dim(df)
>> remove(df)
>> odbcClose(db)
>> remove(db)
>> detach("package:RODBC")
>>
>> Next, I moved that data file (table2006.RData) to another workstation - not
>> at the client site.
>>
>> Now, I need to get that data file into a data.frame object.  I know this
>> should be simple, but I can't seem to find out how to do that.  I tried the
>> following.  First, after opening R without doing anything, RGui used 35,008
>> KB of memory.  I submitted the following.
>>
>>> debt2006<- load("T:/R.Data/table2006.RData")
>> Memory used by RGui jumped to 191,512 KB.  So, it looks like the data
>> loaded.  However, debt2005 is of type character instead of data.frame.
>>
>>> ls()
>> [1] "debt2005"
>>> class(debt2005)
>> [1] "character"
>> Help, please.
>>
> The load/save mechanism handles multiple objects. You can't really assign the result of load(), its return value is just a vector of object names ("df", right?).
>
> So look in your workspace for an object called "df". Then assign it to debt2005. AFAIK, this won't duplicate quite as much as it sounds it might.
>
> For a single-step variation, try something like
>
> debt2005<- local({load(myfile); df})
>
>
>> Ed
>>
>> Ed Heaton
>> Project Manager, Sr. SAS Developer
>> Data and Analytic Solutions, Inc.
>> 10318 Yearling Drive
>> Rockville, MD 20850
>> Office: 301-520-7414
>> eheaton at dasconsultants.com
>> www.dasconsultants.com<http://www.dasconsultants.com/>
>> CMMI ML-2, SBA 8(a)&  SDB, WBE (WBENC), MBE (VA&  MD)
>>
>> ed at heaton.name
>>
>> (Re: http://www.r-project.org/posting-guide.html)
>>
>> ______________________________________________
>> 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.

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

**********
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