[R] Stumped with subsetting

Gabor Grothendieck ggrothendieck at myway.com
Fri Jul 30 04:20:41 CEST 2004

Peter Wilkinson <pwilkinson <at> videotron.ca> writes:

: 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 ?

read.table will read characters in as factors unless you specify otherwise.
See ?read.table and the as.is= argument in particular.

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