[R] Finding unique terms

[Bert Gunter]

Here is a base R solution:
"dat" is the data frame as in Robert's solution.

> aggregate(dat[,3:6], by= dat[1], FUN = sum, na.rm = TRUE)
  STUDENT_ID   PO1M PO1T PO2M PO2T
1    AA15285 287.80  350   37   50
2    AA15286 240.45  330   41   50

Cheers,
Bert



Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Mon, Oct 15, 2018 at 6:42 PM Robert Baer <rbaer using atsu.edu> wrote:

>
>
> On 10/11/2018 5:12 PM, roslinazairimah zakaria wrote:
> > Dear r-users,
> >
> > I have this data:
> >
> > structure(list(STUDENT_ID = structure(c(1L, 1L, 1L, 1L, 1L, 1L,
> > 2L, 2L, 2L, 2L, 2L), .Label = c("AA15285", "AA15286"), class = "factor"),
> >      COURSE_CODE = structure(c(1L, 2L, 5L, 6L, 7L, 8L, 2L, 3L,
> >      4L, 5L, 6L), .Label = c("BAA1113", "BAA1322", "BAA2113",
> >      "BAA2513", "BAA2713", "BAA2921", "BAA4273", "BAA4513"), class =
> > "factor"),
> >      PO1M = c(155.7, 48.9, 83.2, NA, NA, NA, 48.05, 68.4, 41.65,
> >      82.35, NA), PO1T = c(180, 70, 100, NA, NA, NA, 70, 100, 60,
> >      100, NA), PO2M = c(NA, NA, NA, 37, NA, NA, NA, NA, NA, NA,
> >      41), PO2T = c(NA, NA, NA, 50, NA, NA, NA, NA, NA, NA, 50),
> >      X = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA), X.1 = c(NA,
> >      NA, NA, NA, NA, NA, NA, NA, NA, NA, NA)), .Names = c("STUDENT_ID",
> > "COURSE_CODE", "PO1M", "PO1T", "PO2M", "PO2T", "X", "X.1"), class =
> > "data.frame", row.names = c(NA,
> > -11L))
> >
> > I want to combine the same Student ID and add up all the values for PO1M,
> > PO1T,...,PO2T obtained by the same ID.
> >
> > How do I do that?
> > Thank you for any help given.
> >
> oops!  Forgot to clean up after my cut and paste. Solution with dplyr
> looks like this:
> # Create sums by student ID
> library(dplyr)
> dat %>%
>    group_by(STUDENT_ID) %>%
>    summarize(sum.PO1M = sum(PO1M, na.rm = TRUE),
>              sum.PO1T = sum(PO1T, na.rm = TRUE),
>              sum.PO2M = sum(PO2M, na.rm = TRUE),
>              sum.PO2T = sum(PO2T, na.rm = TRUE))
>
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