R help - Nov 2009 - Perform operations on dataframes called with paste in loops

In a loop, I compose the name of a csv file using paste, then read it (e.g.,
dataset1.csv, dataset2.csv, etc). The name of the dataframe assigned to the
imported csv is also composed with paste (e.g., dataset1, dataset2, etc.).
Now I want to perform operations on the dataframes dataset1, dataset2, etc.
However, the paste function only renders a string on which I can not, for
example, do operations like
plot(paste("dataset",i,"[,1]",sep=""),paste("dataset",i,"[,2]",sep="")).
How
could I call the dataframe instead of the string representing its name?

--
Serge-?tienne Parent
Golder Associ?s
Montr?al
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On Nov 17, 2009, at 6:14 PM, separent wrote:
>
> In a loop, I compose the name of a csv file using paste, then read  
> it (e.g.,
> dataset1.csv, dataset2.csv, etc). The name of the dataframe assigned  
> to the
> imported csv is also composed with paste (e.g., dataset1, dataset2,  
> etc.).
> Now I want to perform operations on the dataframes dataset1,  
> dataset2, etc.
> However, the paste function only renders a string on which I can  
> not, for
> example, do operations like
>
plot(paste("dataset",i,"[,1]",sep=""),paste("dataset",i,"[,
> 2]",sep="")). How
> could I call the dataframe instead of the string representing its  
> name?
?get

(It's also in the FAQ.)

-- 
David

separent wrote:
> In a loop, I compose the name of a csv file using paste, then read it
(e.g.,
> dataset1.csv, dataset2.csv, etc). The name of the dataframe assigned to the
> imported csv is also composed with paste (e.g., dataset1, dataset2, etc.).
> Now I want to perform operations on the dataframes dataset1, dataset2, etc.
> However, the paste function only renders a string on which I can not, for
> example, do operations like
>
plot(paste("dataset",i,"[,1]",sep=""),paste("dataset",i,"[,2]",sep="")).
How
> could I call the dataframe instead of the string representing its name?
1. consider to read the csv files into a *list* of dataframes and loop 
over that list.
2. if you do not want to follow 1., see ?get

Uwe Ligges

There are a few options:

You can read the help page for the function that you used to assign names to the
data frames when you read them in (the 'see also' section is there for a
reason).

You can read the FAQ (7.21 to be specific, but the others could save you
re-asking FAQs in the future)

You can take a better approach by reading all your data sets into a list (use
lapply on the vector of names), then use lapply on the list of datasets and
avoid all the future headache/heartache that will come from the approach you are
trying.

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of separent
> Sent: Tuesday, November 17, 2009 4:15 PM
> To: r-help at r-project.org
> Subject: [R] Perform operations on dataframes called with paste in
> loops
> 
> 
> In a loop, I compose the name of a csv file using paste, then read it
> (e.g.,
> dataset1.csv, dataset2.csv, etc). The name of the dataframe assigned to
> the
> imported csv is also composed with paste (e.g., dataset1, dataset2,
> etc.).
> Now I want to perform operations on the dataframes dataset1, dataset2,
> etc.
> However, the paste function only renders a string on which I can not,
> for
> example, do operations like
>
plot(paste("dataset",i,"[,1]",sep=""),paste("dataset",i,"[,2]",sep=""))
> . How
> could I call the dataframe instead of the string representing its name?
> --
> View this message in context: http://old.nabble.com/Perform-operations-
> on-dataframes-called-with-paste-in-loops-tp26399586p26399586.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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