From: Peter Wilkinson <pwilkinson_at_videotron.ca>

Date: Fri 30 Jul 2004 - 06:03:26 EST

R-help@stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 30 06:07:47 2004

Date: Fri 30 Jul 2004 - 06:03:26 EST

Hi there,

thanks for the reply. I was expecting what Tony posted. By the way I got the format for my question out of Introduction to R. So I expected it to work as in the text, but it turns out ....

my "list" somehow was not a vector:

> list[1]

**[1] PERH0125
**

44 Levels: PERH0015 PERH0019 PERH0023 PERH0029 PERH0037 PERH0045 PERH0053
**PERH0075 ... PERH0360
**
I did the following:

> list2 = as.vector(list)

> list2

** [1] "PERH0125" "PERH0315" "PERH0161" "PERH0181" "PERH0229" "PERH0223"
**
**"PERH0243" "PERH0269"
**

<snip>

I am not sure what format list was in (looks like factor), but I turned it into a vector and it worked as expected. I have to go back and see how I created list in the first place.

originally I took a row from a data frame, removed NA values, then sorted it into an order that I wanted (using 'order') .... so I don't know when it turned into something that looked like factor. Any ?

Peter

At 03:46 PM 7/29/2004, Sundar Dorai-Raj wrote:

>Sundar Dorai-Raj wrote:

*>
**>>
**>>Peter Wilkinson wrote:
**>>
**>>>This seems like such a trivial thing to do:
**>>>
**>>>given a data.frame DF and variables w,v, x,y,z I can do
**>>>
**>>>DF["x"] or DF[c("x","y")]
**>>>
**>>>if I create a vector, mylist = c("x",y")
**>>>
**>>>then I do DF[mylist]
**>>>
**>>>I am not getting x and y, I get something else.
**>>>
**>>>
**>>>what is the correct way to subset a data.frame by columns using a
**>>>vector, as if I were doing DF["x","y"]?
**>>>
**>>>Peter
**>>>
**>>>______________________________________________
**>>>R-help@stat.math.ethz.ch mailing list
**>>>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
**>>>PLEASE do read the posting guide!
**>>>http://www.R-project.org/posting-guide.html
**>>
**>>You want DF[, mylist]. DF[mylist] returns a list. You may want to look at
**>>"An Introduction to R", which covers this topic.
**>
**>Sorry, typed too quickly.
**>
**>DF[mylist] and DF[, mylist] are the same if mylist is a vector with more
**>than one element.
**>
**>After re-reading your post, I'm not quite sure what you are expecting.
**>Sorry for any confusion....
**>
**>--sundar
**>
*

R-help@stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 30 06:07:47 2004

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