read TXT files

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• 1How to read TXT files in R?

  • 1.1 Skip rows of a TXT file

  • 1.2 How to identify NULL values in a TXT file?

  • 1.3 Import TXT from URL

• 2 Download TXT file in R

  How to read TXT files in R?

  You can read a TXT file in R with the read.table function. Importing TXT into R rarely needs more arguments than specified. In the following subsections we will explain two more (skip and skipNul) if needed, but in case you want to know all the arguments you can find them in the read.table function documentation or calling ?read.table. This basic syntax affects to almost all TXT data files.

  Basic syntax
  read.table(file,    # TXT data file indicated as string                               or full path to the file           
           header = FALSE,    # Whether to display the header (TRUE)                            or not (FALSE)            
           sep = "",          # Separator of the columns of the file          dec = ".")         # Character used to separate decimals                             of the numbers in the file

  Consider, for instance, that yo have a TXT file called my_file.txt and you have put it in your R working directory. You can read it with the following code if you want to also display the header (column names).

  data <- read.table(file = "my_file.txt", header = TRUE)
  head(data)

  ##    x       y
  ## 1 10 34.7081
  ## 2 12 34.5034
  ## 3 14 36.5656
  ## 4 16 38.3125
  ## 5 18 42.5441
  ## 6 20 43.7210

  `In case you have the file in other directory than your working directory, you will need to specify the full path where the data file

  data <- read.table(file = “C:\My_path\my_file.txt”, header = TRUE) data <- read.table(file = “C:/My_path/my_file.txt”, header = TRUE) # Equivalent

  There also two functions (read.delim and read.delim2) to deal with delimited files by default. This functions have the following default arguments:

  Syntax
  read.delim(file = "my_file.txt" header = TRUE, sep = "\t", dec = ".")
  read.delim2(file = "my_file.txt", header = TRUE, sep = "\t", dec = ",")

  Function	Header	Sep	Dec
  read.table	FALSE	""	"."
  read.delim	TRUE	"\t"	"."
  read.delim2	TRUE	"\t"	","

  Skip rows of a TXT file

  Sometimes the TXT files you are reading contain some lines of text before the dataset. To solve this issue you can use the skip argument, that defaults to 0. Consider, for instance, that there are 5 lines of text before your data, so you can read the file the following way:

  read.table(file = "my_file.txt", skip = 5)

  ##    V1      V2
  ## 1  18 42.5441
  ## 2  20 43.7210
  ## 3  22 45.7065
  ## 4  24 46.4718
  ## 5  26 49.7821
  ## 6  28 51.1522
  ## 7  30 55.1607
  ## 8  32 54.7800
  ## 9  34 56.9059
  ## 10 36 59.5827
  ## 11 38 61.4808
  ## 12 40 65.4764
  ## 13 42 65.8270
  ## 14 44 66.5816
  ## 15 46 68.5623
  ## 16 48 72.0188
  ## 17 50 73.1321

  How to identify NULL values in a TXT file?

  If your TXT data contains NULL values, you can set the skipnul argument to TRUE to

  read.table(file = “C:\My_path\my_file”, skipnul = TRUE)

  Import TXT from URL

  In case you have a TXT file hosted in some website, you can open it without downloading it. You just need to pass the URL as string to the first argument.

  url <- "http://courses.washington.edu/b517/Datasets/string.txt"
  data <- read.table(url, header = TRUE)
  head(data)

  ##    x       y
  ## 1 10 34.7081
  ## 2 12 34.5034
  ## 3 14 36.5656
  ## 4 16 38.3125
  ## 5 18 42.5441
  ## 6 20 43.7210

  Download TXT file in R

  Now that you know how to read a TXT in R, it should be noticed that you can directly download a TXT file in R to your working directory with the download.file function, passing the link as the first argument and the name you want to put to the .txt file as the second.

  getwd() # Path where the file will be downloaded

  ## [1] "C:/Users/immju/OneDrive/Documents"

  url <- "http://courses.washington.edu/b517/Datasets/string.txt"
  download.file(url, "my_file.txt")

  If you don't want to download the file to the working directory, you can specify the path where you want the file to be downloaded.

  download.file(url, "C:\\folder\\my_file.txt")

  ## Warning in download.file(url, "C:\\folder\\my_file.txt"): URL
  ## http://courses.washington.edu/b517/Datasets/string.txt: cannot open destfile
  ## 'C:\folder\my_file.txt', reason 'No such file or directory'

  ## Warning in download.file(url, "C:\\folder\\my_file.txt"): download had nonzero
  ## exit status

• Note that the echo = FALSE parameter was added to the code chunk to prevent printing of the R code that generated the plot.