How to read in multiple data tables in R using the apply function?
I am relatively new to R and I am having a problem reading multiple tables from a directory using the apply function. What I would like to use is to use a vector with the paths to the tables I am interested in and generate a list with objects consisting of each data frame corresponding to the paths in that file. I wrote the following code:
f<- function(directory){
file.list <<- list.files(directory)
file.paths <<- as.vector(paste(directory, file.list, sep = "/"))
tables <- lapply(X = file.paths, FUN = read.table, header = TRUE,sep = "\t" ))
}
According to my understanding, I am doing the creation of a list of filenames in the directory I want by creating a path to those files and (where I fail) iterate over those paths and import the tables they match to the entire file.paths object and generate a list with those tables. I am getting the following error:
Error in FUN(X[[i]], ...) : no lines available in input
Can anyone suggest any advice?
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Here are several options depending on what you want:
List of data frames
# Load library
library(data.table)
# Get a List of all files named with a key word, say all `.csv` files
filenames <- list.files("C:/your/folder", pattern="*.csv", full.names=TRUE)
# Load data sets
list.DFs <- lapply(filenames,fread)
I am assuming your data files are saved in .csv
. Note that it is fread
equivalent read.table
but much faster
Concatenate multiple data frames in one data frame
# Get a List of all files named with a key word, say all `.csv` files
filenames <- list.files("C:/your/folder", pattern="*.csv", full.names=TRUE)
# Load and bind all data sets
data <- rbindlist(lapply(filenames,fread))
Loading multiple data frames into different objects in the global environment
# Get a List of DF in the directory
filenames <- list.files("C:/your/folder", pattern="*.Rda", full.names=TRUE)
# Load data sets
lapply(filenames, load, .GlobalEnv)
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