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: yoursurrogate...@gmail.com
|> > Sent: Sun, 22 Mar 2015 10:39:03 -0400
|> > To: r-help@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]]
|> >
|> > ______________________________________________
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______________________________________________
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