Section 6 Read Data

6.1 Function

Function	Explanation
setwd	Set the working directory. Note the file path is given by / or \\.
getwd	Get the current working directory. Note the file path is given by / or \\.
read.table	Read a tabular data - it reads a file in table format and creates a data frame from it, with lines and variables to fields in the file. It is always convenient to assign the outputs from read.table to an R object.
read.csv	Read a csv file. It is always convenient to assign the outputs from read.csv to an R object.
readLines	Read lines of a text file
source	Read the R script file

6.2 Example

?read.table

read.table(file, header = FALSE, sep = "", quote = "\"'",
           dec = ".", numerals = c("allow.loss", "warn.loss", "no.loss"),
           row.names, col.names, as.is = !stringsAsFactors,
           na.strings = "NA", colClasses = NA, nrows = -1,
           skip = 0, check.names = TRUE, fill = !blank.lines.skip,
           strip.white = FALSE, blank.lines.skip = TRUE,
           comment.char = "#",
           allowEscapes = FALSE, flush = FALSE,
           stringsAsFactors = default.stringsAsFactors(),
           fileEncoding = "", encoding = "unknown", text, skipNul = FALSE)

read.csv(file, header = TRUE, sep = ",", quote = "\"",
         dec = ".", fill = TRUE, comment.char = "", ...)

• Note:
  • The R function attach attaches variables of a dataframe in the global environment. Although the function provides convenience, brevity and simplicity, it is generally not a good programming practice. DO NOT USE attach in your R script.
  • Data are read using connection interfaces. Connections are commonly made to files or to other formats like url, gzfile, bzfile etc.
    
  • The foreign library supports reading data in several proprietary formats.