Here’s where I’m stumped -
when I call mutate(test, place = substr(test$subject, 1,3)) to create a place
variable, I get this, with place as a character variable.
subject group wk1 wk2 wk3 wk4 place
(fctr) (fctr) (int) (int) (int) (int) (chr)
1 001-002 boys 2 3 4 5 001
2 002-003 boys 7 6 5 4 002
3 003-004 boys 9 4 6 1 003
4 004-005 girls 5 7 8 9 004
5 005-006 girls 2 6 3 8 005
6 006-007 girls 1 4 7 4 006
When I call test$place <- factor(test$place), I receive the msg - "Error in
`$<-.data.frame`(`*tmp*`, "place", value = integer(0)) :
replacement has 0 rows, data has 6.
If I call mutate this way - mutate(test, place =
factor(substr(test$subject,1,3))), I get the same output as above but when I
call class(test$place), I get NULL and the variable disappears.
I can’t figure out why.
Ken
kmna...@gmail.com
914-450-0816 (tel)
347-730-4813 (fax)
> On Mar 4, 2016, at 3:46 PM, Jeff Newmiller <jdnew...@dcn.davis.ca.us> wrote:
>
> I much prefer the factor function over the as.factor function for converting
> character to factor, since you can set the levels in the order you want them
> to be.
> --
> Sent from my phone. Please excuse my brevity.
>
> On March 4, 2016 10:07:27 AM PST, Sarah Goslee <sarah.gos...@gmail.com> wrote:
> As everyone has been telling you, as.factor().
> If you like the mutate approach, you can call as.factor(test$subject)
> to convert it.
>
> Here's a one-liner with reproducible data.
>
>
> testdata <- structure(list(subject = structure(1:6, .Label = c("001-002",
> "002-003", "003-004", "004-005", "005-006", "006-007"), class = "factor"),
> group = structure(c(1L, 1L, 1L, 2L, 2L, 2L), .Label = c("boys",
> "girls"), class = "factor"), wk1 = c(2L, 7L, 9L, 5L, 2L,
> 1L), wk2 = c(3L, 6L, 4L, 7L, 6L, 4L), wk3 = c(4L, 5L, 6L,
> 8L, 3L, 7L), wk4 = c(5L, 4L, 1L, 9L, 8L, 4L)), .Names = c("subject",
> "group", "wk1", "wk2", "wk3", "wk4"), class = "data.frame", row.names = c(NA,
> -6L))
>
> testdata$subject <- as.factor(substring(as.character(testdata$subject), 1, 3))
>
>
> testdata
> subject group wk1 wk2 wk3 wk4
> 1 001 boys 2 3 4 5
> 2 002 boys 7 6 5 4
> 3 003 boys 9 4 6 1
> 4 004 girls 5 7 8 9
> 5 005 girls 2 6 3 8
> 6 006 girls 1 4 7 4
> str(testdata)
> 'data.frame': 6 obs. of 6 variables:
> $ subject: Factor w/ 6 levels "001","002","003",..: 1 2 3 4 5 6
> $ group : Factor w/ 2 levels "boys","girls": 1 1 1 2 2 2
> $ wk1 : int 2 7 9 5 2 1
> $ wk2 : int 3 6 4 7 6 4
> $ wk3 : int 4 5 6 8 3 7
> $ wk4 : int 5 4 1 9 8 4
>
> Sarah
>
> On Fri, Mar 4, 2016 at 1:00 PM, KMNanus <kmna...@gmail.com> wrote:
>
> Here’s the dataset
> I’m working with, called test -
>
> subject group wk1 wk2 wk3 wk4 place
> 001-002 boys 2 3 4 5
> 002-003 boys 7 6 5 4
> 003-004 boys 9 4 6 1
> 004-005 girls 5 7 8 9
> 005-006 girls 2 6 3 8
> 006-007 girls 1 4 7 4
>
>
> if I call mutate(test, place = substr(subject,1,3), “001 is the first
> observation in the place column
>
> But it’s a character and “subject” is a factor. I need place to be a
> factor, too, but I need the observations to be ONLY the first three numbers
> of “subject.”
>
> Does that make my request more understandable?
>
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> <http://www.r-project.org/posting-guide.html>
> and provide commented, minimal,
> self-contained, reproducible code.
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