R attach Function


attach() function makes the data available to the R Search Path.

attach(x)
x: dataframe, matrix, list

Following file has been used for ANOVA analysis:
(Download the data file)

Let first read in the data from the file:
>x <- read.csv("anova.csv",header=T,sep=",")

There are 3 variables, "Expression", "Gender" and "Subtype". We can display the variables by:
>x$Gender
  [1] m m m m m f m m f m m f m m m m f m m m m m m f m m m f m m m m f m m m m
 [38] m m m m m m m m m f m f m m m m m f m m f m m f m m m m f m m m m m m m m
 [75] m m f m m m m m f m m m m m m m m m f m m f m m f m f m m f m m f m m f m
[112] m f m m f m m m f m m m f m f m f f f f f f m f m f f f m f f f f m f m f
[149] m f f m f f f f f m f m f f m f f m f f m f f f m f f f m f f f m f f m f
[186] f f m f f m f m m f m f m f f m f f f f f m f f m f f f m m m f m m m f f
[223] f f f f f m m m f m f f m f f f m f f f m f f f f m f m f f f f m f f f m
[260] f f m f f f f f f m f f m f f f f f f m f f
Levels: f m

We can't use the variable "Gender" in R Search Path:
>gender
Error: object 'Gender' not found

After attach the object "x", "Gender" can be used globally:
>attach(x)
>Gender
  [1] m m m m m f m m f m m f m m m m f m m m m m m f m m m f m m m m f m m m m
 [38] m m m m m m m m m f m f m m m m m f m m f m m f m m m m f m m m m m m m m
 [75] m m f m m m m m f m m m m m m m m m f m m f m m f m f m m f m m f m m f m
[112] m f m m f m m m f m m m f m f m f f f f f f m f m f f f m f f f f m f m f
[149] m f f m f f f f f m f m f f m f f m f f m f f f m f f f m f f f m f f m f
[186] f f m f f m f m m f m f m f f m f f f f f m f f m f f f m m m f m m m f f
[223] f f f f f m m m f m f f m f f f m f f f m f f f f m f m f f f f m f f f m
[260] f f m f f f f f f m f f m f f f f f f m f f
Levels: f m

detach() function reverses the process:
>detach(x)
>Gender
Error: object 'Gender' not found