R help - Feb 2006 - How to get all the data in a specific column from a dataframe?

Dear R-helpers:

Suppose I have a datafram called "test_frame" like this
     col1   col2  col3  col4
r1   x        x        x     x
r2   x        x        x     x
r3   x        x        x     x
..    x        x        x     x
rn   x        x        x     x

I know I can get data of col3 by using test_frame[,3].

My question is, if I want to do this by specifying "col3" rather than
3,
what should I do?

Many thanks....

	[[alternative HTML version deleted]]

test_frame[,"col3"]

or

subset(test_frame, select = col3)

Vincent Deng wrote:
> Dear R-helpers:
> 
> Suppose I have a datafram called "test_frame" like this
>      col1   col2  col3  col4
> r1   x        x        x     x
> r2   x        x        x     x
> r3   x        x        x     x
> ..    x        x        x     x
> rn   x        x        x     x
> 
> I know I can get data of col3 by using test_frame[,3].
> 
> My question is, if I want to do this by specifying "col3" rather
than 3,
> what should I do?
> 
> Many thanks....
> 
> 	[[alternative HTML version deleted]]
> 
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