R help - Mar 2015 - Why can't I access this type?

> On Mar 25, 2015, at 10:14, Henric Winell <nilsson.henric at
gmail.com> wrote:
> 
>> On 2015-03-25 09:40, Patrick Connolly wrote:
>> 
>> On Sun, 22-Mar-2015 at 08:06AM -0800, John Kane wrote:
>> 
>> |> Well, first off, you have no variable called "Name". 
You have lost
>> |> the state names as they are rownames in the matrix state.x77 and
>> |> not a variable.
>> |>
>> |> Try this. It's ugly and I have no idea why I had to do a
cbind()
>> 
>> You don't have to use cbind
>> 
>> |> but it seems to work. Personally I find subset easier to read
than
>> |> the indexing approach.
>> 
>> |> state  <-  rownames(state.x77)
>> |> all.states <- as.data.frame(state.x77)
>> |> all.states  <-  cbind(state, all.states) ### ?????
>> 
>> You don't have to use cbind()
>> 
>> all.states  <- within(as.data.frame(state.x77), state <-
rownames(state.x77))
>> 
>> but I think cbind is simpler to read.
>> 
>> |>
>> |> coldstates  <-   subset(all.states, all.states$Frost > 50,
>> |>                         select =
c("state","Frost") )
> 
> I find the indexing approach
> 
> coldstates <- all.states[all.states$Frost > 150,
c("state","Frost")]
> 
> to be the most direct and obvious solution.
> 
>> Tidier, even more so than subset():
>> 
>> require(dplyr)
>> coldstates <- all.states %>% filter(Frost > 150) %>%
select(state, Frost)
>> 
>> Or, easier to see what's happening:
>> 
>> coldstates <- all.states %>%
>>   filter(Frost > 150) %>%
>>   select(state, Frost)
> 
> Well...  Opinions may perhaps differ, but apart from '%>%' being
butt-ugly it's also fairly slow:
> 
> > library("microbenchmark")
> > microbenchmark(
> +     subset(all.states, all.states$Frost > 150, select =
c("state","Frost")),
> +     all.states[all.states$Frost > 150,
c("state","Frost")],
> +     all.states %>% filter(Frost > 150) %>% select(state, Frost),
> +     times = 1000L
> + )
> Unit: microseconds
>   expr
> subset(all.states, all.states$Frost > 150, select = c("state",
"Frost"))
>                       all.states[all.states$Frost > 150,
c("state", "Frost")]
>                   all.states %>% filter(Frost > 150) %>%
select(state, Frost)
>      min       lq      mean    median        uq      max neval cld
>  139.112  148.673  163.3960  159.1760  170.7895 1763.200  1000  b
>  104.039  111.973  127.2138  120.4395  128.6640 1381.809  1000 a
> 1010.076 1033.519 1133.1469 1107.8480 1175.1800 2932.206  1000   c
> 
> Of course, this doesn't matter for interactive one-off use.  But lately
I've seen examples of the '%>%' operator creeping into functions
in packages.  However, it would be nice to see a fast pipe operator as part of
base R.
> 
> 
> Henric Winell
> 
> 
> 
>> 
>> 
>> |>
>> |>
>> |> John Kane
>> |> Kingston ON Canada
>> |>
>> |>
>> |> > -----Original Message-----
>> |> > From: yoursurrogategod at gmail.com
>> |> > Sent: Sun, 22 Mar 2015 10:39:03 -0400
>> |> > To: r-help at r-project.org
>> |> > Subject: [R] Why can't I access this type?
>> |> >
>> |> > Hi, I'm just learning my way around R.  I got a bunch of
states and would
>> |> > like to access to get all of the ones where it's cold. 
But when I do the
>> |> > following, I will get the following error:
>> |> >
>> |> >> all.states <- as.data.frame(state.x77)
>> |> >> cold.states <- all.states[all.states$Frost > 150,
c("Name", "Frost")]
>> |> > Error in `[.data.frame`(all.states, all.states$Frost >
150, c("Name",  :
>> |> >   undefined columns selected
>> |> >
>> |> > I don't get it.  When I look at all.states, this is what
I see:
>> |> >
>> |> >> str(all.states)
>> |> > 'data.frame':   50 obs. of  8 variables:
>> |> >  $ Population: num  3615 365 2212 2110 21198 ...
>> |> >  $ Income    : num  3624 6315 4530 3378 5114 ...
>> |> >  $ Illiteracy: num  2.1 1.5 1.8 1.9 1.1 0.7 1.1 0.9 1.3 2
...
>> |> >  $ Life Exp  : num  69 69.3 70.5 70.7 71.7 ...
>> |> >  $ Murder    : num  15.1 11.3 7.8 10.1 10.3 6.8 3.1 6.2 10.7
13.9 ...
>> |> >  $ HS Grad   : num  41.3 66.7 58.1 39.9 62.6 63.9 56 54.6
52.6 40.6 ...
>> |> >  $ Frost     : num  20 152 15 65 20 166 139 103 11 60 ...
>> |> >  $ Area      : num  50708 566432 113417 51945 156361 ...
>> |> >
>> |> > What am I messing up?
>> |> >
>> |> >    [[alternative HTML version deleted]]
>> |> >
>> |> > ______________________________________________
>> |> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and
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>> |> > https://stat.ethz.ch/mailman/listinfo/r-help
>> |> > PLEASE do read the posting guide
>> |> > http://www.R-project.org/posting-guide.html
>> |> > and provide commented, minimal, self-contained, reproducible
code.
>> |>
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see
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>> |> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>> |> and provide commented, minimal, self-contained, reproducible
code.

I agree with you on the indexing approach.  But even after using within, I still
get the same error.
>

On Thu, 26-Mar-2015 at 04:58PM -0400, yoursurrogategod at gmail.com wrote:

[...]
|>  I agree with you on the indexing approach.  But even after using
|> within, I still get the same error.  >

You leave us to guess just what you tried, but if you did this:
> all.states  <- within(as.data.frame(state.x77), state <-
rownames(state.x77))
and then again did this:
> cold.states <- all.states[all.states$Frost > 150, c("Name",
"Frost")]
of course it will give the same error, because as you haven't
addressed the problem as you've been told

On Sun, 22-Mar-2015 at 08:06AM -0800, John Kane wrote:

|> Well, first off, you have no variable called "Name".  You have
lost
|> the state names as they are rownames in the matrix state.x77 and
|> not a variable.

If you did this:
> all.states  <- within(as.data.frame(state.x77), Name <-
rownames(state.x77))
instead of
> all.states  <- within(as.data.frame(state.x77), state <-
rownames(state.x77))
then this would worka;
> cold.states <- all.states[all.states$Frost > 150, c("Name",
"Frost")]
Modify the above to match where my guess at what you tried is in error.


HTH

-- 
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
 {~._.~}                   Great minds discuss ideas    
 _( Y )_  	         Average minds discuss events 
(:_~*~_:)                  Small minds discuss people  
 (_)-(_)  	                      ..... Eleanor Roosevelt
	  
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.

On 2015-03-27 09:19, Patrick Connolly wrote:
> [...]
>
> On Sun, 22-Mar-2015 at 08:06AM -0800, John Kane wrote:
>
> |> Well, first off, you have no variable called "Name".  You
have lost
> |> the state names as they are rownames in the matrix state.x77 and
> |> not a variable.
>
> If you did this:
>
>> all.states  <- within(as.data.frame(state.x77), Name <-
rownames(state.x77))
> instead of
>> all.states  <- within(as.data.frame(state.x77), state <-
rownames(state.x77))
Alternatively, since 'data.frame()' coerces internally, one could do

all.states <- data.frame(state.x77, Name = rownames(state.x77))


Henric Winell


>
> then this would worka;
>> cold.states <- all.states[all.states$Frost > 150,
c("Name", "Frost")]
>
> Modify the above to match where my guess at what you tried is in error.
>
>
> HTH
>