The post is about how to import data using read.table() function. You will also learn what is a file path and how to get and set the working directory in R language.
Question: How I can check my Working Directory so that I would be able to import my data in R? Answer: To find the working directory, the command getwd() can be used, that is
getwd()
Question: How I can change the working directory to my path?
Answer: Use function setwd(), that is
setwd("d:/mydata")
setwd("C:/Users/XYZ/Documents")Question: I have a data set stored in text format (ASCII) that contains rectangular data. How I can read this data in tabular form? I have already set my working directory.
Answer: As data is already in a directory, which is set as the working directory, use the following command to import the data using read.table() command.
mydata <- read.table("data.dat")
mydata <- read.table("data.txt")The mydata is a named object that will have data from the file “data.dat” or “data.txt” in data frame format. Each variable in the data file will be named by default V1, V2,…
Question: How this stored data can be accessed?
Answer: To access the stored data, write the data frame object name (“mydata”) with the $ sign and name of the variable. That is,
mydata$V1 mydata$V2 mydata["V1"] mydata[ , 1]
Question: My data file has variable names in the first row of the data file. In the previous Question, variables names were V1, V2, V3, … How I can get the actual names of the variables stored in the first row of the data.dat file?
Answer: Instead of reading a data file with default values of arguments, use
read.table("data.dat", header = TRUE)Question: I want to read a data file that is not stored in the working directory.
Answer: To access the data file that is not stored in the working directory, provide a complete path of the file, such as.
read.table("d:/data.dat" , header = TRUE)
read.table("d:/Rdata/data.txt" , header = TRUE)Note that read.table() is used to read the data from external files that have normally a special form:
- The first line of the file should have a name for each variable in the data frame. However, if the first row does not contain the name of a variable then the header argument should not be set to FALSE.
- Each additional line of the file has its first item a row label and the values for each variable.
In R it is strongly suggested that variables need to be held in the data frame. For this purpose read.table() function can be used. For further details about read.table() function use,
help(read.table)