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Reputation: 331

R: Applying readRDS to a list object of .Rds file names

I have several .Rds files containing data frame objects and I want to apply a function to each file and bind the data frames into a single data frame. However, when I try to read in multiple .Rds file from a list of file names, I receive the error:

Error in FUN(X[[i]], ...) : error reading from connection

Does readRDS not work with lists?

########################
# Reproducible example
########################

library(dplyr)

# Create .Rds files
saveRDS(data.frame(a = seq(1:3), b = rep("a",3)),"a.Rds")
saveRDS(data.frame(a = seq(9:11), b = c("j","h","o")),"b.Rds")

# Create list of file names to read
rds <- list("a.Rds","b.Rds")

# Read in .Rds files (error occurs here)
temp <- lapply(rds, readRDS)

# Converts file to single data frame
final <- do.call(dplyr::bind_rows, temp)

Upvotes: 3

Views: 5016

Answers (1)

Wolfgang
Wolfgang

Reputation: 584

In the purrr package the function map_df does what you want. map_df returns a single dataframe by row-binding the individual elements.

saveRDS(data.frame(a = 1:3, b = rep("a",3)),"a.Rds")
saveRDS(data.frame(a =9:11, b = c("j","h","o")),"b.Rds")

# Create list of file names to read
rds <- c("a.Rds","b.Rds")

library(purrr)
purrr::map_df(rds, readRDS)

The edited version corrects a small error in the example.

Upvotes: 2

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