How to save() with a particular variable name

Question

I am repeatedly applying a function to read and process a bunch of csv files. Each time it runs, the function creates a data frame (this.csv.data) and uses save() to write it to a .RData file with a unique name. Problem is, later when I read these .RData files using load(), the loaded variable names are not unique, because each one loads with the name this.csv.data....

I'd like to save them with unique tags so that they come out properly named when I load() them. I've created the following code to illustrate .

this.csv.data = list(data=c(1:9), unique_tag = "some_unique_tag")
assign(this.csv.data$unique_tag,this.csv.data$data)
# I want to save the data, 
# with variable name of <unique_tag>, 
# at a file named <unique_tag>.dat
saved_file_name <- paste(this.csv.data$unique_tag,"RData",sep=".")
save(get(this.csv.data$unique_tag), saved_file_name)

but the last line returns:

"Error in save(get(this_unique_tag), file = data_tag) : 
  object ‘get(this_unique_tag)’ not found"

even though the following returns the data just fine:

get(this.csv.data$unique_tag)

I think you could also take a look at the envir argument in load() to retain the original column names if they are important. If you don't need to process multiple files at one time, couldn't you rm() the object after your analysis before moving on to the next file? — Chase
– Chase, Commented Jan 13, 2011 at 1:41
@Chase, the column names still seem to come out fine, it's the duplicated names of the created dataframes that was the issue. In the long run I anticipate rbinding these data frames into one big one and as you suggest it may be I don't need them more than one at a time. — J. Win.
– J. Win., Commented Jan 13, 2011 at 3:24

daroczig · Accepted Answer · 2011-01-13 01:33:08Z

35

Just name the arguments you use. With your code the following works fine:

save(list = this.csv.data$unique_tag, file=saved_file_name)

edited Jan 13, 2011 at 1:33

answered Jan 13, 2011 at 1:16

daroczig

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3 Comments

J. Win. Over a year ago

It "works" in that it doesn't return an error, but when I load(saved_file_name) it creates a variable called "whattosave" instead of "unique_tag" After loading ten files, I would only have the latest "whattosave" instead of ten unique variables...

daroczig Over a year ago

@jonw - sorry I was too inattentive. I edited my answer, hope it will really work!

IRTFM Over a year ago

@jonw; Hey,shouldn't you be giving darczig the answer check?

Charles · Accepted Answer · 2011-01-13 03:29:09Z

28

My preference is to avoid the name in the RData file on load:

obj = local(get(load('myfile.RData')))

This way you can load various RData files and name the objects whatever you want, or store them in a list etc.

answered Jan 13, 2011 at 3:29

Charles

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1 Comment

Franck Dernoncourt Over a year ago

That'd be nice to explain what local and get do.

Karl Forner · Accepted Answer · 2013-11-07 09:57:31Z

16

You really should use saveRDS/readRDS to serialize your objects. save and load are for saving whole environments.

saveRDS(this.csv.data, saved_file_name)
# later
mydata <- readRDS(saved_file_name)

answered Nov 7, 2013 at 9:57

Karl Forner

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Comments

Zoe - Save the data dump · Accepted Answer · 2018-10-06 08:24:32Z

0

you can use

save.image("myfile.RData")

edited Oct 6, 2018 at 8:24

Zoe - Save the data dump

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answered Oct 6, 2018 at 4:35

minitechi

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Comments

dfrankow · Accepted Answer · 2020-07-28 20:53:47Z

0

This worked for me:

env <- new.env()
env[[varname]] <- object_to_save
save(list=c(varname), envir=env, file='out.Rda')

You could probably do it without a new env (but I didn't try this):

.GlobalEnv[[varname]] <- object_to_save
save(list=c(varname), envir=.GlobalEnv, file='out.Rda')

You might even be able to remove the envir variable.

answered Jul 28, 2020 at 20:53

dfrankow

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