[R] using underscore character in column names

[Terry Westley]

Suppose you're reading data from a file in which the
column names contain underscore characters.  Example:

------ start of file -----
pos_x   pos_y
  1.0     0.0
  2.0     1.0
------ end of file -------

Using read.table, I can read this file just fine:

> data <- read.table (file="data", head=T)
> data
  pos_x pos_y
1     1     0
2     2     1
> 

However, I can't refer to pox_x because the _ character
is an alternative to <- (assignment):

> data$pos_x
Error: Object "x" not found

I could use data[1], but I'd prefer to use the column
name.  Must I change all my column names to remove the
underscore character or is there way to force R to
recogize the whole column name?

Something like data${pos_x} or data$pos\_x  ???

--
Terry J. Westley, Software Systems Engineering Supervisor
Veridian Engineering, Calspan Operations
P.O. Box 400, Buffalo, NY 14225
twestley at buffalo.veridian.com    http://www.veridian.com

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