Lapply with read_csv - r

Question

I am having trouble understanding lapply with read_csv function. The question is if Lapply creates an array of dataframes where I can access each dataframe using data[i]?
What I did:
I have downloaded the 5 cities data set (found here: https://archive.ics.uci.edu/ml/machine-learning-databases/00394/FiveCitiePMData.rar) and wrote R code to extract the 5 csv files and save to a dataframe as follows:
cities <- list.files('FiveCities')
cities_df <- lapply(cities, read.csv)
My goal was to create a workbook and save each of the csv files into an xlsx file with each csv being a sheet in the workbook as follows:
wb <- createWorkbook()
for(i in 1:length(cities)){
sheet <- addWorksheet(wb , i)
writeData(wb, sheet, cities_df[i])
}
What I am confused on is accessing each csv like this cities_df[i]. I thought cities_df[i] accesses the ith row of the dataframe and not a separate dataframe as a whole. Does lapply create an array of dataframes called cities_df[i] or what happens? If it does create an array then how come I can simply call cities_df and receive a result without specifying which dataframe in the array to call?

Answer 1

Here is complete code to create the Excel workbook and save it to a file FiveCities/cities.xlsx.
cities <- list.files('FiveCities', full.names = TRUE)
cities_df <- lapply(cities, read.csv)
names(cities_df) <- sub("\\.csv", "", basename(cities))
wb <- createWorkbook()
for(i in names(cities_df)){
sheet <- addWorksheet(wb , i)
writeData(wb, i, cities_df[[i]])
}
saveWorkbook(wb, file = "FiveCities/cities.xlsx")

Answer 2

This code may help!
library(plyr)
library(readr)
library(tidyverse)
library(openxlsx)
mydir = "C:/Users/mouad/Desktop/assasins creed/new"
myfiles = list.files(path=mydir, pattern="*.csv", full.names=TRUE)
str_length(mydir)
mylist=lapply(1:5, function(j) read_csv(myfiles[[j]]))
setwd(mydir)
wb <- createWorkbook()
lapply(1:length(mylist), function(i){
addWorksheet(wb=wb, sheetName = substr(myfiles[i],str_length(mydir)+1,60))
writeData(wb, sheet = i, mylist[[i]][length(mylist[[i]])])
})
saveWorkbook(wb, "test.xlsx", overwrite = TRUE)
read.xlsx("test.xlsx", sheet = 1)