R for loop dataframe variable names

Question

I am new to R and loops. I have a data frame (xyz). I am running a loop and want to save a new new data frames under different names.

states <- c("AL",   "AK")
keywords <- c("snow", "rain")
filepath <- file.path("C:/data/")

for(state_var in states) 
for(key_var in keywords) 
{
save(xyz, file = (file.path(filepath, paste0(state_var, sep = "_", key_var,".RData"))))
}

Everything is working perfectly and new data frame is saved under different names. But when I load saved data frames all data frames have exactly same name xyz.

How it is possible to save under different df name. Thanks a lot.

I was just using load(file.path(filepath, "AL_snow.RData")) — Behzod A
– Behzod A, Commented May 24, 2020 at 15:42

Jan · Accepted Answer · 2020-05-24 16:08:52Z

2

Try this:

states <- c("AL",   "AK")
keywords <- c("snow", "rain")

for(state_var in states) 
  for(key_var in keywords) 
  {
    objname <- paste(state_var, key_var, sep="_")
    assign(objname, xyz)
    save(list = objname, file = (file.path(filepath, paste0(state_var, sep = "_", key_var,".RData"))))
    rm(objname) # make sure you get rid of this again
  }

Save stores the saved object as is. That includes the name. With assign you create a new variable with the name you want.

edited May 24, 2020 at 16:08

answered May 24, 2020 at 12:40

Jan

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2 Comments

Behzod A Over a year ago

Hi @Jan I am getting following error: object ‘assign("objname", xyz)’ not found

Jan Over a year ago

You're right. Wow! Fascinating!! The object existed but somehow save wasn't able to work with it. I fixed it. Tested it to the end this time.

Behzod A · Accepted Answer · 2020-05-24 16:10:39Z

1

Thank you for everyone. I was able to solve this question. It turns that assign does not work inside the function. And we have to use the list. Here is the solution:

states <- c("AL",   "AK")
keywords <- c("snow", "rain")
filepath <- file.path("C:/data/")

for(state_var in states) 
for(key_var in keywords) 
{
assign(paste(state_var, key_var, sep="_"), xyz)
save(list = paste(state_var, key_var, sep="_"), file = (file.path(filepath, paste0(state_var, sep = "_", key_var,".RData"))))
}

answered May 24, 2020 at 16:10

Behzod A

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