Iteratively save .Rds data.frame objects with R

Question

I need to save iteratively data.frame objects on drive.

A similar issue was already posted here but ultimately, and to my point of view, missed the answer because:

1. The author of the question correctly asked to save the data.frame as .Rds file, but ended up writing code about .Rda;
2. The author of the accepted answer uses save() whereas saveRDS() should have been used. Failing to do so, command readRDS won't read corresponding files.

My question:

• What piece of code do I need in order to iteratively save .Rds files?

Answer 1

Here below is a piece of, hopefully reproducible, piece of code (with comments) that worked very well for me (links in comments are where code has been found to adapt to situation):

# 1. Load some data from the Internet and close connections
library(quantmod)
tickers <- c("SHOP", "MPNGF", "BABA", "JD")
getSymbols.yahoo(tickers, auto.assign = TRUE, env = globalenv())
closeAllConnections()


# 2. Find all loaded xts files
xtsObjects <- names(which(unlist(eapply(.GlobalEnv, is.xts))))


# 3. Iteratively convert found xts files under 2. into data.frames
# https://stackoverflow.com/a/69246047/2950721
library(zoo)
for (i in seq_along(xtsObjects)) {
  assign(xtsObjects[i], fortify.zoo(get(xtsObjects[i])))
}

# 4. Iteratively save converted data.frame objects as .Rds files
# https://stackoverflow.com/a/8345810/2950721
# https://stackoverflow.com/a/69246047/2950721
library(fs)
rdsFilesFolder <- path("rdsFiles")
saveRDSobjects <- paste0("./", rdsFilesFolder, "/", xtsObjects, ".Rds")

for (i in seq_along(xtsObjects)) {
  saveRDS(get(xtsObjects[i]), file = saveRDSobjects[i])
}

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System used:

• R version: 4.1.1 (2021-08-10)
• RStudio version: 1.4.1717
• OS: macOS Catalina version 10.15.7