How to clean multiple excel files in one time in R? - r

Question

I have more than one hundred excel files need to clean, all the files in the same data structure. The code listed below is what I use to clean a single excel file. The files' name all in the structure like 'abcdefg.xlsx'
library('readxl')
df <- read_excel('abc.xlsx', sheet = 'EQuote')
# get the project name
project_name <- df[1,2]
project_name <- gsub(".*:","",project_name)
project_name <- gsub(".* ","",project_name)
# select then needed columns
df <- df[,c(3,4,5,8,16,17,18,19)]
# remane column
colnames(df)[colnames(df) == 'X__2'] <- 'Product_Models'
colnames(df)[colnames(df) == 'X__3'] <- 'Qty'
colnames(df)[colnames(df) == 'X__4'] <- 'List_Price'
colnames(df)[colnames(df) == 'X__7'] <- 'Net_Price'
colnames(df)[colnames(df) == 'X__15'] <- 'Product_Code'
colnames(df)[colnames(df) == 'X__16'] <- 'Product_Series'
colnames(df)[colnames(df) == 'X__17'] <- 'Product_Group'
colnames(df)[colnames(df) == 'X__18'] <- 'Cat'
# add new column named 'Project_Name', and set value to it
df$project_name <- project_name
# extract rows between two specific characters
begin <- which(df$Product_Models == 'SKU')
end <- which(df$Product_Models == 'Sub Total:')
## set the loop
in_between <- function(df, start, end){
return(df[start:end,])
}
dividers = which(df$Product_Models %in% 'SKU' == TRUE)
df <- lapply(1:(length(dividers)-1), function(x) in_between(df, start =
dividers[x], end = dividers[x+1]))
df <-do.call(rbind, df)
# remove the rows
df <- df[!(df$Product_Models %in% c("SKU","Sub Total:")), ]
# remove rows with NA
df <- df[complete.cases(df),]
# remove part of string after '.'
NeededString <- df$Product_Models
NeededString <- gsub("\\..*", "", NeededString)
df$Product_Models <- NeededString
Then I can get a well structured datafram.Well Structured Dataframe Example
Can you guys help me to write a code, which can help me clean all the excel files at one time. So, I do not need to run this code hundred times. Then, aggregating all the files into a big csv file.

Answer 1

You can use lapply (base R) or map (purrr package) to read and process all of the files with a single set of commands. lapply and map iterate over a vector or list (in this case a list or vector of file names), applying the same code to each element of the vector or list.
For example, in the code below, which uses map (map_df actually, which returns a single data frame, rather than a list of separate data frames), file_names is a vector of file names (or file paths + names, if the files aren't in the working directory). ...all processing steps... is all of the code in your question to process df into the form you desire:
library(tidyverse) # Loads several tidyverse packages, including purrr and dplyr
library(readxl)
single_data_frame = map_df(file_names, function(file) {
df = read_excel(file, sheet="EQUOTE")
... all processing steps ...
df
}
Now you have a single large data frame, generated from all of your Excel files. You can now save it as a csv file with, for example, write_csv(single_data_frame, "One_large_data_frame.csv").
There are probably other things you can do to simplify your code. For example, to rename the columns of df, you can use the recode function (from dplyr). We demonstrate this below by first changing the names of the built-in mtcars data frame to be similar to the names in your data. Then we use recode to change a few of the names:
# Rename mtcars data frame
set.seed(2)
names(mtcars) = paste0("X__", sample(1:11))
# Look at data frame
head(mtcars)
# Recode three of the column names
names(mtcars) = recode(names(mtcars),
X__1="New.1",
X__5="New.5",
X__9="New.9")
Or, if the order of the names is always the same, you can do (using your data structure):
names(df) = c('Product_Models','Qty','List_Price','Net_Price','Product_Code','Product_Series','Product_Group','Cat')
Alternatively, if your Excel files have column names, you can use the skip argument of read_excel to skip to the header row before reading in the data. That way, you'll get the correct column names directly from the Excel file. Since it looks like you also need to get the project name from the first few rows, you can read just those rows first with a separate call to read_excel and use the range argument, and/or the n_max argument to get only the relevant rows or cells for the project name.