Error when during merging excel files in r with blank sheet - r

Question

I'm using the following code to merge several excel files with multiple sheets. I get an error when it runs across a sheet that has the same header as the other files but is not populated with data. This is the error:
Error in data.frame(sub.id, condition, s.frame, ss) :
arguments imply differing number of rows: 0, 2
How can I avoid the error? Here is the code I am using below.
file.names <- list.files(pattern='*.xls')
sheet.names <- getSheets(loadWorkbook('File.xls'))
sheet.names <-sheet.names[1:12]
e.names <- paste0(rep('v', 16), c(1:16))
data.1 <- data.frame(matrix(rep(NA,length(e.names)),
ncol = length(e.names)))
names(data.1) <- e.names
for (i in 1:length(file.names)) {
wb <- loadWorkbook(file.names[i])
for (j in 1:length(sheet.names)) {
ss <- readWorksheet(wb, sheet.names[j], startCol = 2, header = TRUE)
condition <- rep(sheet.names[j], nrow(ss))
sub.id <- rep(file.names[i], nrow(ss))
s.frame <- seq(1:nrow(ss))
df.1 <- data.frame(sub.id, condition, s.frame, ss)
names(df.1) <- e.names
data.1 <- rbind(data.1, df.1)
rm(ss, condition, s.frame, sub.id, df.1)
}
rm(wb)
}

Answer 1

I suppose this solution will work for you. It loads all .xlsx files in a specified folder into a list of lists. Sheet-names and -headers shouldn't be an issue.
library(openxlsx)
# Define folder where your files are
path_folder <- "C:/path_to_files/"
# load file names into a list
f <- list.files(path_folder)
f <- ifelse(substring(f,nchar(f)-4,nchar(f))==".xlsx",f,NA)
f <- f[!is.na(f)]
data_list <- as.list(f)
# get sheet-names
names(data_list) <- data_list
data_list <- lapply(data_list, function(x){getSheetNames(paste0(path_folder, x))})
# load data into a list of lists
data_list <- lapply(data_list, function(x){as.list(x)})
data_list <- lapply(names(data_list),function(x){
sapply(data_list[[x]],function(y){read.xlsx(paste0(path_folder, x),sheet=y)})
})
# name the list elements
names(data_list) <- gsub(".xlsx", "", f)
You end up with a list (containing each file) of lists (containing the sheets of each file).
From here you can remove empty sheets, merge and edit them as you like.

Answer 2

Added an if-statement to check if there was more than one row if not skip reading in and it resolved the error.
for (i in 1:length(file.names)) {
wb <- loadWorkbook(file.names[i])
for (j in 1:length(sheet.names)) {
ss <- readWorksheet(wb, sheet.names[j], startCol = 2, header = TRUE)
if (nrow(ss) > 1)
{
condition <- rep(sheet.names[j], nrow(ss))
sub.id <- rep(file.names[i], nrow(ss))
s.frame <- seq(1:nrow(ss))
df.1 <- data.frame(sub.id, condition, s.frame, ss)
names(df.1) <- e.names
data.1 <- rbind(data.1, df.1)
rm(ss, condition, s.frame, sub.id, df.1)
}
}
rm(wb)
}