Exporting to Text Files

As mentioned in the importing data section, text files are a popular way to hold and exchange tabular data as almost any data application supports exporting data to the CSV (or other text file) formats. Consequently, exporting data to a text file is a pretty standard operation. Plus, since you’ve already learned how to import text files you pretty much have the basics required to write to text files…we just use a slightly different naming convention.

Similar to the examples provided in the importing text files section, the two main groups of functions that I will demonstrate to write to text files include base R functions and readr package functions.

• Base R functions
• readr package functions

Base R functions

write.table() is the multipurpose work-horse function in base R for exporting data. The functions write.csv() and write.delim() are special cases of write.table() in which the defaults have been adjusted for efficiency. To illustrate these functions let’s work with a data frame that we wish to export to a CSV file in our working directory.

df <- data.frame(var1 = c(10, 25, 8), 
                 var2 = c("beer", "wine", "cheese"), 
                          var3 = c(TRUE, TRUE, FALSE),
                 row.names = c("billy", "bob", "thornton"))

df
##          var1   var2  var3
## billy      10   beer  TRUE
## bob        25   wine  TRUE
## thornton    8 cheese FALSE

To export df to a CSV file we can use write.csv(). Additional arguments allow you to exclude row and column names, specify what to use for missing values, add or remove quotations around character strings, etc.

# write to a csv file
write.csv(df, file = "export_csv")

# write to a csv and save in a different directory
write.csv(df, file = "/folder/subfolder/subsubfolder/export_csv")

# write to a csv file with added arguments
write.csv(df, file = "export_csv", row.names = FALSE, na = "MISSING!")

In addition to CSV files, we can also write to other text files using write.table and write.delim().

# write to a tab delimited text files
write.delim(df, file = "export_txt")

# provides same results as read.delim
write.table(df, file = "export_txt", sep="\t")

readr package

The readr package uses write functions similar to base R. However, readr write functions are about twice as fast and they do not write row names. One thing to note, where base R write functions use the file = argument, readr write functions use path =.

library(readr)

# write to a csv file
write_csv(df, path = "export_csv2")

# write to a csv and save in a different directory
write_csv(df, path = "/folder/subfolder/subsubfolder/export_csv2")

# write to a csv file without column names
write_csv(df, path = "export_csv2", col_names = FALSE)

# write to a txt file without column names
write_delim(df, path = "export_txt2", col_names = FALSE)